Chemistry Quiz: Refine Designs Using Chemical Evidence

20 questions · exam conditions

0:00

Refine Designs Using Chemical EvidenceQuestion 1 of 20

A cafeteria tested a new food-storage wrap. The initial design used a thin PVC-based film because it clings well and is inexpensive.

Test results:

The wrap prevented moisture loss well (good).
When used on oily foods (pizza, cheese) for 2 hours, several students reported a "plastic" taste.
When used on dry foods (bread) for 2 hours, no taste was reported.

Which refinement best addresses the problem indicated by the evidence while keeping the moisture barrier benefit?

Make the PVC film thicker so more plastic flavor is trapped inside the wrap

Add a thin inert barrier layer (or switch to a food-grade polymer with lower additive migration) designed for contact with oily foods

Poke small holes in the wrap to let the taste escape

Store oily foods at higher temperature so the wrap clings more tightly

← Back to quizzes

Chemistry Quiz

Chemistry Quiz: Refine Designs Using Chemical Evidence

Practice Refine Designs Using Chemical Evidence in Chemistry with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Refine Designs Using Chemical Evidence, giving you a quick way to practice the rules, question types, and explanations that matter most for Chemistry.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A cafeteria tested a new food-storage wrap. The initial design used a thin PVC-based film because it clings well and is inexpensive.

Test results:

The wrap prevented moisture loss well (good).
When used on oily foods (pizza, cheese) for 2 hours, several students reported a "plastic" taste.
When used on dry foods (bread) for 2 hours, no taste was reported.

Which refinement best addresses the problem indicated by the evidence while keeping the moisture barrier benefit?

Make the PVC film thicker so more plastic flavor is trapped inside the wrap
Add a thin inert barrier layer (or switch to a food-grade polymer with lower additive migration) designed for contact with oily foods (correct answer)
Poke small holes in the wrap to let the taste escape
Store oily foods at higher temperature so the wrap clings more tightly

Question 2

A school lab designed a container for storing dilute hydrochloric acid (0.5 M). Their initial container used a steel screw cap with a rubber gasket on a glass bottle because it sealed tightly.

After 3 months:

The steel cap showed rust and pitting on the inside surface.
The rubber gasket became brittle and cracked.
The glass bottle itself remained unchanged.

Which refinement best targets the chemical compatibility problems shown?

Replace the steel cap with a plastic cap (e.g., polypropylene) and use an acid-resistant gasket material while keeping the glass bottle (correct answer)
Use a larger steel cap so the acid has more space and is less reactive
Switch from glass to aluminum so the bottle is lighter
Add baking soda to the acid so the cap stops rusting

Question 3

A team designs a clear protective cover for an outdoor sensor. Design 1 uses a clear polystyrene sheet because it is inexpensive and easy to cut. After 2 months in direct sunlight, the cover turns yellow and becomes brittle, cracking during a light bend test. An identical cover kept indoors stays clear and flexible.

Which refinement best uses the evidence to improve the design for outdoor use?

Switch to a UV-resistant plastic (e.g., acrylic or polycarbonate with UV stabilizers) or add a UV-protective coating while keeping the cover clear (correct answer)
Make the polystyrene cover thinner so it absorbs less sunlight
Paint the cover black so yellowing is not visible
Add ventilation holes so air can cool the cover, even though the main problem is sunlight exposure

Question 4

An engineering class designs a small container to store $0.5\,\text{M}$ hydrochloric acid for a lab kit. Initial design: an aluminum bottle with a screw cap was chosen because aluminum is lightweight and easy to machine. Test evidence (48-hour storage): white pitting spots formed inside the bottle, and the mass of the empty bottle decreased by 0.6 g after rinsing and drying. The cap seal remained tight (no leaks at the threads).

Which refinement best targets the chemical cause of the problem shown by the evidence?

Use a glass (borosilicate) or HDPE bottle instead of aluminum, keeping the same volume and cap style (correct answer)
Polish the aluminum interior to make it smoother so acid cannot stick to it
Make the aluminum walls thicker so the pitting takes longer to go through
Add extra grooves to the screw threads to improve the seal, since the acid is escaping

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence indicates chemical corrosion of aluminum by hydrochloric acid, causing pitting and mass loss, with no issues in sealing, so refinement should replace the material with an acid-resistant alternative like glass or HDPE. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like B or C attempt to mitigate corrosion but fail to eliminate the reactive aluminum-acid interaction, which is the core issue per the pitting and mass data, while D incorrectly targets sealing despite evidence of no leaks. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (pitting and mass loss = acid corrosion). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (aluminum not acid-resistant). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to inert glass/HDPE). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If cap seals well, keep style. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed corrosion → change material). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: aluminum bottle for acid. Test: pitting. Evidence: acid attacks aluminum. Refinement: switch to glass/HDPE. Test refined design. This is cheaper and faster than redesigning the container!

Question 5

A student designs a small "heat pack" demonstration using a sealed pouch of calcium chloride that warms when water is added. Design 1 uses a thin latex balloon as the pouch because it is flexible and easy to tie. In testing, several balloons become weak and burst within 5 minutes after the calcium chloride dissolves. The temperature inside reaches about 50°C, and the outside of the balloon feels slippery.

Which refinement is most likely to prevent failure based on the evidence?

Use a thicker latex balloon so it stretches more before bursting
Replace the latex with a more chemically resistant, heat-tolerant pouch material (e.g., a polyethylene bag designed for warm liquids) and double-seal the edges (correct answer)
Add more calcium chloride so the balloon warms faster and is done sooner
Cool the balloon in ice water first so it starts at a lower temperature

Question 6

A student builds a simple water filter using activated carbon held in place by a foam pad. The filter removes odor well at first, but after one week the foam pad swells and begins to crumble when exposed to chlorinated tap water. A test shows the foam loses 12% of its mass after soaking in chlorinated water for 7 days, while a polypropylene (PP) mesh loses 0% mass and stays intact. Which refinement best targets the failure mode shown by the evidence?

Replace the foam pad with polypropylene mesh to support the carbon without degrading in chlorinated water (correct answer)
Add more activated carbon so the foam pad is less important
Use hotter water during filtration so the foam pad expands less
Color the foam pad black so crumbling is harder to see

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The evidence reveals the foam pad degrades (swells and crumbles) in chlorinated water with mass loss, while PP mesh remains stable, pointing to inadequate chemical resistance to chlorine. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence—switching to resistant PP mesh—while maintaining successful aspects of original design like supporting activated carbon. Choice D fails because coloring the foam masks crumbling but doesn't prevent degradation or maintain functionality. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (material corroded = corrosion resistance insufficient, material melted = thermal stability inadequate, material reacted = chemical inertness needed, material leached = toxicity concern). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (not resistant enough to acid/base, not stable at operating temperature, too reactive with contents, not inert enough). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to more resistant material, increase temperature rating, use inert alternative, add protective barrier). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If material is right price and right strength but wrong chemical resistance, change ONLY the resistance part if possible (coating, substitute similar material). Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed cracking in cold → add cold-resistant formulation). REDESIGN = starting over (doesn't work at all → try completely different approach). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: plastic pipe for drain. Test: works fine with water, cracks with drain cleaner (strong base). Evidence: base attacks this plastic. Refinement: switch to base-resistant plastic (PVC → polypropylene) OR add inert liner. Test refined design. This is cheaper and faster than completely redesigning the drain system!

Question 7

A student designs a copper wire electrode for an electrolysis demonstration in saltwater (NaCl solution). The copper electrode works initially, but after two class periods it becomes pitted and the solution turns blue-green. A graphite electrode tested in the same setup stays intact and the solution remains clear. Based on this evidence, what refinement best improves the design for repeated classroom use?

Replace the copper electrode with graphite to reduce electrode corrosion in saltwater electrolysis (correct answer)
Use a thicker copper wire so the blue-green color is less noticeable
Increase the voltage so electrolysis finishes faster and the copper has less time to corrode
Paint the copper wire with a water-soluble paint so it looks cleaner during the demo

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The evidence shows copper corrodes in saltwater electrolysis, pitting and coloring the solution, while graphite remains stable, highlighting inadequate corrosion resistance in copper. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence—switching to inert graphite—while maintaining successful aspects of original design for classroom demos. Choice C fails because higher voltage might accelerate corrosion, not address the reactivity issue. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (material corroded = corrosion resistance insufficient, material melted = thermal stability inadequate, material reacted = chemical inertness needed, material leached = toxicity concern). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (not resistant enough to acid/base, not stable at operating temperature, too reactive with contents, not inert enough). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to more resistant material, increase temperature rating, use inert alternative, add protective barrier). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If material is right price and right strength but wrong chemical resistance, change ONLY the resistance part if possible (coating, substitute similar material). Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed cracking in cold → add cold-resistant formulation). REDESIGN = starting over (doesn't work at all → try completely different approach). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: plastic pipe for drain. Test: works fine with water, cracks with drain cleaner (strong base). Evidence: base attacks this plastic. Refinement: switch to base-resistant plastic (PVC → polypropylene) OR add inert liner. Test refined design. This is cheaper and faster than completely redesigning the drain system!

Question 8

An outdoor sign was printed on steel and protected with a clear coating. The initial coating was a hard, brittle clear lacquer chosen because it resisted scratching.

Field test over one winter:

Areas exposed to road salt spray developed rust streaks at small cracks in the coating.
The coating remained clear (no yellowing), but many hairline cracks appeared after repeated freeze–thaw cycles.
A small test panel using a more flexible polyurethane clear coat showed fewer cracks but slightly more surface scratching.

Which refinement best targets the failure mode shown by the evidence?

Use a more flexible clear coat (e.g., polyurethane) or add a flexible primer layer to reduce cracking that allows saltwater to reach the steel (correct answer)
Make the steel sheet thicker so rust cannot form through it as quickly
Remove the coating entirely so it cannot crack
Add blue dye to the clear coat so rust streaks are less visible

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The field test evidence indicates rust from saltwater penetrating cracks in the brittle coating caused by freeze-thaw cycles, while a flexible polyurethane showed fewer cracks, so refinement should focus on coating flexibility to prevent cracking without sacrificing too much scratch resistance. Choice A proposes an appropriate refinement by targeting the specific chemical property problem identified in test evidence—using a more flexible clear coat to reduce cracking and saltwater ingress—while maintaining the protective coating concept. Choice B fails because thicker steel delays rust but doesn't address the evidence-based cause of coating cracks allowing saltwater access, making it an untargeted change. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (cracks in coating leading to rust = flexibility insufficient). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (coating too brittle for temperature cycles). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to flexible coating). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If scratch resistance is good but flexibility lacks, adjust for flexibility. Great job analyzing— you're refining like a pro!

Question 9

A student team designs a reusable spray bottle to hold a homemade bathroom cleaner containing 5% acetic acid (vinegar) and a small amount of salt. They choose an uncoated steel spring for the trigger because steel is strong and inexpensive. After 2 weeks of daily use, the trigger becomes stiff and orange-brown rust appears on the spring. The bottle still seals and does not leak.

Based on the test results, which refinement would best address the failure while keeping the trigger strong?

Make the steel spring thicker so it takes longer to rust through
Replace the steel spring with a stainless steel spring (or add a corrosion-resistant coating) to reduce rusting in acidic, salty solution (correct answer)
Increase the amount of salt in the cleaner so the spring dries faster after use
Switch the bottle body from plastic to glass so the spring is less likely to corrode

Question 10

Two glove materials were tested for a lab activity using dilute ammonia solution (a weak base). The goal is safe handling for 30-minute labs while keeping good dexterity.

Test results:

Latex gloves: remained flexible, but after 30 minutes developed a slight sticky feel and a strong odor.
Nitrile gloves: no stickiness or odor after 60 minutes, but students reported slightly less flexibility.

Which refinement best uses the evidence to improve the design choice for the lab?

Choose nitrile gloves for ammonia handling, since they showed better chemical resistance in testing, and select a thinner nitrile grade to improve dexterity (correct answer)
Choose latex gloves and increase ammonia concentration so the gloves are tested under harsher conditions
Use no gloves and wash hands afterward, since odor is the only issue
Double-layer latex gloves to improve dexterity while keeping the same chemical resistance

Question 11

A team built a simple solar oven and covered the inner walls with aluminum foil tape to reflect heat. They used a common adhesive-backed foil tape.

Testing:

At $90\,^{\circ}\mathrm{C}$ , the tape stayed attached.
At $120\,^{\circ}\mathrm{C}$ , the adhesive softened and the foil began to peel off.
The oven needs to reach $130\,^{\circ}\mathrm{C}$ for cooking.

Which refinement best addresses the failure shown by the test data?

Replace the tape with a high-temperature adhesive or mechanically fasten the reflective foil so it stays attached at $130\,^{\circ}\mathrm{C}$ (correct answer)
Use darker foil so it absorbs more sunlight and hides peeling
Add water inside the oven to keep the temperature below $100\,^{\circ}\mathrm{C}$
Use thinner foil tape so it peels off more evenly

Question 12

A school lab orders squeeze bottles for $3\%$ hydrogen peroxide. Initial design: natural rubber (latex) tubing is used inside the cap as a dip tube because it is flexible and cheap. Test evidence (1 month): the dip tube becomes sticky and swollen, and small rubber particles appear in the peroxide. The bottle body (HDPE) remains unchanged.

Which refinement best addresses the chemical incompatibility shown in the test results?

Replace the natural rubber dip tube with silicone or polyethylene tubing that is more resistant to oxidation (correct answer)
Make the rubber dip tube thicker so it takes longer to swell
Store the bottles in brighter light so the peroxide breaks down before it reaches the tubing
Add a stronger fragrance to the peroxide to cover any rubber smell

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence demonstrates oxidative degradation of natural rubber by hydrogen peroxide, causing swelling and particles, while the HDPE bottle is unaffected, so refinement should switch to an oxidation-resistant tubing material. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like B or C delay or accelerate degradation but fail to resolve the incompatibility, which is the root cause per the swelling and particles, while D masks symptoms without fixing. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (swelling and particles = oxidative attack). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (rubber not oxidation-resistant). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to resistant tubing). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If bottle works, keep it. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed degradation → change tubing). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: rubber tube in peroxide. Test: swelling. Evidence: oxidation. Refinement: switch to silicone/PE. Test refined design. This is cheaper and faster than redesigning the bottle!

Question 13

A student designed a container to store bleach (sodium hypochlorite solution) and chose a clear PET plastic bottle because it is strong and transparent.

Observations during a 6-week storage test in a sunny window:

The bleach lost strength faster than expected (less effective cleaning).
The bottle became slightly yellow and more brittle.
The same bleach stored in an opaque HDPE bottle kept its strength longer.

Which refinement best matches the evidence?

Switch to an opaque, bleach-compatible plastic (such as HDPE) or add a UV-blocking/opaque layer to reduce light-driven degradation (correct answer)
Keep the clear PET bottle but add sugar to the bleach to stabilize it
Use a thinner PET bottle so less plastic can turn yellow
Store the bleach at a higher temperature so it reacts faster during cleaning

Question 14

A team designs a refillable water bottle for athletes. Initial design: an unlined aluminum bottle was selected because it is lightweight and conducts heat well (keeps drinks cold when chilled). Test evidence: When filled with a sports drink (contains citric acid, pH ≈ 3.5), the drink develops a metallic taste after 24 hours, and the inside surface shows dull spots. When filled with plain water, no taste change occurs.

Which refinement best addresses the evidence while keeping the bottle lightweight and reusable?

Add an inert interior lining/coating (e.g., food-grade epoxy or polymer liner) to isolate the acidic drink from the aluminum (correct answer)
Make the aluminum thicker so less metal dissolves into the drink
Add more citric acid to the sports drink so the taste is dominated by sourness instead of metal
Roughen the interior surface so any dull spots are less visible

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence indicates acid corrosion of unlined aluminum, leading to metallic taste and dull spots with acidic drinks but not water, so refinement should isolate the metal from the acid via a lining. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like B or C reduce dissolution rate or mask taste but fail to prevent the corrosion interaction, which is the core issue per the taste and spots, while D addresses visibility not the cause. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (taste and spots with acid = corrosion). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (aluminum not acid-resistant). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (add inert lining). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If lightweight and cooling work, keep them. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed corrosion → add liner). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: unlined aluminum for acid drink. Test: metallic taste. Evidence: acid attacks aluminum. Refinement: add epoxy liner. Test refined design. This is cheaper and faster than new bottle material!

Question 15

A class designs a container to mix and store a basic cleaning solution (contains sodium hydroxide, pH ≈ 13). Initial design: a glass jar with a metal (steel) lid was chosen because glass is chemically resistant and transparent. Test evidence (3-week use): the glass remains clear, but the lid develops rust and becomes difficult to open; brown residue appears around the lid threads. The solution itself still cleans well.

Which refinement best addresses the failure shown by the evidence while keeping the benefits of the original design?

Switch to a jar made entirely of steel so the lid and jar match and expand the same amount
Keep the glass jar but replace the steel lid with a plastic lid (PP/HDPE) or a corrosion-resistant lid with an inert liner (correct answer)
Tighten the steel lid more strongly each time so air cannot reach the threads
Add food coloring to the cleaning solution so any rust is less noticeable

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence shows corrosion of the steel lid by basic NaOH, causing rust and seizing, while the glass jar remains intact, so refinement should replace the lid with a corrosion-resistant alternative. Choice B proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like A or C switch to all-steel (which would corrode) or tighten more but fail to address the base-metal reaction, which is the root cause per the rust and residue, while D masks visuals not the issue. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (rust on lid = base corrosion). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (steel not base-resistant). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to plastic lid). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If glass works, keep it. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed lid rust → change lid). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: glass jar with steel lid for base. Test: rust. Evidence: base attacks steel. Refinement: use plastic lid. Test refined design. This is cheaper and faster than all-new container!

Question 16

A student designs a protective coating for a steel bike rack near the ocean. Initial design: a standard acrylic paint was selected because it is inexpensive and easy to apply. Test evidence (8-week salt-spray exposure): rust appears first at scratches and edges; flat painted areas remain mostly rust-free. The paint film is still attached (no large peeling), but rust creeps under the coating from damaged spots.

Which refinement would most directly address the failure mode shown by the evidence?

Apply a zinc-rich primer under the acrylic topcoat to provide sacrificial corrosion protection at scratches and edges (correct answer)
Use a glossier acrylic paint so water beads up more on the surface
Paint the rack a darker color so it warms in the sun and dries faster
Increase the thickness of the acrylic topcoat only on the flat surfaces, since those areas are performing well

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence shows corrosion starting at scratches and edges with undercutting, while flat areas hold up, indicating the need for sacrificial protection against salt-induced rust in damaged spots. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like B or C focus on water repellency or drying but fail to address the galvanic corrosion and undercutting at edges, which is the primary failure mode per the evidence, while D unnecessarily thickens well-performing areas. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (rust at scratches = inadequate protection in damaged areas). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (no sacrificial corrosion resistance). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (add zinc primer). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If flat areas work, keep the topcoat. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed edge rust → add primer). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: acrylic on steel. Test: rust at scratches. Evidence: salt attacks exposed steel. Refinement: add zinc primer. Test refined design. This is cheaper and faster than repainting everything!

Question 17

A student designs a container for storing solid calcium chloride (a drying agent). Initial design: a steel tin with a snap-on lid was chosen because it is strong and cheap. Test evidence (2 weeks in a humid room): the calcium chloride clumps and partially dissolves; rust spots appear on the inside of the tin near the lid seam. The lid feels loose after repeated opening.

Which refinement would best address the evidence-based problems while keeping the container reusable?

Replace the steel tin with a sealed plastic jar (HDPE or PP) that has a gasketed screw cap to reduce moisture entry and prevent rust (correct answer)
Keep the steel tin but drill small holes near the top so moisture can escape
Keep the steel tin and add salt water to the calcium chloride so it clumps less
Paint only the outside of the tin so it looks nicer and is easier to label

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence reveals moisture absorption by hygroscopic CaCl2 causing clumping, rust on steel, and lid loosening, so refinement should switch to a non-corrosive, better-sealed plastic container. Choice A proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like B or C introduce ventilation or additives that worsen moisture issues or mismatch the corrosion evidence, while D addresses appearance not functionality. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (rust and clumping = moisture-induced corrosion). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (steel not moisture-resistant, poor seal). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to sealed plastic). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If strength and cost work, choose similar. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed rust → change to plastic). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: steel tin for CaCl2. Test: rust and clumping. Evidence: moisture attacks steel. Refinement: use sealed HDPE jar. Test refined design. This is cheaper and faster than redesigning storage!

Question 18

A company prototypes a clear lid for a salad container. Initial design: a polystyrene (PS) lid was chosen because it is cheap and clear. Test evidence: When the lid is used on salads containing an oil-and-vinegar dressing, student taste testers report a "plastic" flavor after 2 hours. The lid stays rigid and does not warp. When the same lid is used on dry crackers, no taste change is reported.

Which refinement best addresses the problem indicated by the evidence while keeping the lid clear and low-cost?

Make the polystyrene lid thicker so fewer molecules can pass through it
Add a thin food-safe inert barrier layer (e.g., a PET or EVOH lining) on the underside of the lid that contacts the food (correct answer)
Add ventilation holes so the salad dries out and cannot absorb plastic flavor
Switch to an aluminum lid to prevent any taste transfer, even if it is not transparent

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence reveals migration of polystyrene components into oily dressings, causing off-flavors, but not with dry foods, so refinement should add a barrier to prevent contact while keeping clarity and cost low. Choice B proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like A or D address thickness or material switch but mismatch the evidence of molecular migration (not structural failure), with D sacrificing transparency, while C introduces unrelated drying that could harm the salad. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (flavor transfer with oils = migration through plastic). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (not inert to oils). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (add barrier layer). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If clarity and rigidity work, keep them. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed migration → add liner). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: PS lid for oily food. Test: off-flavor. Evidence: migration into oils. Refinement: add inert barrier. Test refined design. This is cheaper and faster than switching entirely!

Question 19

A student team designs a reusable spray bottle for a citrus-based degreaser (contains d-limonene and other organic solvents). Initial design: a clear polycarbonate (PC) bottle was chosen because it is impact-resistant and transparent. Test evidence (2-week use test): the bottle developed fine cracks around the neck and trigger threads, and a faint solvent smell was noticed outside the bottle even when closed. Mass of the filled bottle decreased by 1.8% over 14 days at room temperature. The trigger still works and the bottle does not shatter.

Based on the evidence, which refinement would best address the failure mode while keeping the bottle reusable?

Increase the polycarbonate wall thickness so it is harder to crack, keeping the same plastic and cap design
Switch the bottle material to HDPE (high-density polyethylene) while keeping the same shape and trigger assembly (correct answer)
Add a blue dye to the polycarbonate so UV light cannot reach the degreaser
Replace the trigger sprayer with a metal one to make the neck area stronger, keeping the polycarbonate bottle

Explanation: This question tests your ability to use evidence from testing and observations to refine engineering designs by identifying chemical property inadequacies and proposing targeted modifications that address specific problems. Design refinement is the engineering practice of using test results and evidence to improve solutions through iteration: when testing reveals problems (material corrodes, degrades, reacts, fails under conditions), you don't start over completely—instead, you make targeted changes that address the specific issues while preserving aspects that worked well. The key is connecting evidence to refinement: if tests show plastic container cracked after acid exposure (evidence), the refinement must address acid resistance specifically (switch to acid-resistant material or add protective coating), not make random changes. Good refinements are evidence-based (data shows the problem), targeted (fixes specific issue, not everything), and feasible (realistic with available materials/methods). This is how real engineering works—iterative improvement based on testing! The test evidence shows chemical incompatibility between the polycarbonate and organic solvents in the degreaser, leading to cracking, permeation, and mass loss, so refinement should focus on a more solvent-resistant material without altering functional aspects like shape and trigger. Choice B proposes appropriate refinement by targeting the specific chemical property problem identified in test evidence while maintaining successful aspects of original design. Choices like A or D focus on mechanical strength but fail to address the solvent permeation and chemical attack, which is the root cause shown by the smell and mass decrease, while C mismatches the evidence by assuming UV degradation instead of solvent interaction. The evidence-to-refinement process: (1) ANALYZE EVIDENCE: What specific problem does testing reveal? (cracks and permeation = solvent resistance insufficient). Be specific about what failed! (2) IDENTIFY CAUSE: What chemical property is inadequate? (not resistant to organic solvents). Connect failure to missing property. (3) TARGET REFINEMENT: What change addresses that specific property inadequacy? (switch to solvent-resistant HDPE). Refinement must logically fix the identified cause. (4) PRESERVE SUCCESSES: Keep aspects that worked well—don't throw out everything! If trigger works, keep it. Efficient refinement targets problems specifically! Refinement vs redesign: REFINEMENT = targeted modification based on specific evidence (test showed solvent attack → switch material). For most test-based improvements, refinement is appropriate: you learned something from testing (what works, what doesn't), so use that learning to make smart modifications. Example sequence: Design 1: polycarbonate bottle for solvent. Test: cracks and leaks. Evidence: solvent degrades PC. Refinement: switch to HDPE. Test refined design. This is cheaper and faster than redesigning the entire bottle!

Question 20

A student designed a small water bottle with a straw made of natural rubber because it was flexible and cheap.

Testing with different drinks:

With plain water: no smell or taste after 1 day.
With lemon sports drink (acidic): after 1 day, the straw had a noticeable odor and the drink tasted slightly "rubbery."
With the same lemon drink in a silicone straw: no odor/taste change after 1 day.

Which refinement is most supported by the evidence?

Keep natural rubber but add food coloring to the drink so the rubber taste is less noticeable
Replace the natural rubber straw with silicone (or another inert, food-grade polymer) to reduce leaching in acidic drinks (correct answer)
Make the rubber straw longer so less of it touches the drink
Use a metal straw made of ordinary steel to avoid polymers entirely