Evidence of New Substance Formed
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5th Grade Science › Evidence of New Substance Formed
Based on the observations, Student A says, “A new substance formed because the mixture changed from clear to green.” The student mixed 50 mL of blue sports drink with 50 mL of yellow sports drink. The temperature stayed at 20°C, no bubbles formed, and the smell stayed the same. Is Student A’s reasoning correct?
No, because chemical changes only happen when a solid is mixed with a liquid.
No, because the green color can be explained by mixing two colors, with no other reaction signs.
Yes, because the temperature stayed the same, which proves a reaction happened.
Yes, because any color change is always evidence of a chemical change.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically evaluating whether evidence supports new substance formation and distinguishing predictable color mixing from chemical change. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. For this question, blue + yellow drinks making green with no other changes - predictable physical color mixing, not chemical change. Choice B is correct because it correctly recognizes that green color can be explained by simple color mixing (blue + yellow = green) without any other reaction signs, showing the student understands to look for multiple indicators and that predictable color mixing is physical. Choice A represents a common error where students think any color change is always evidence of chemical change, which typically happens because students may focus on most obvious change (color) without checking for additional evidence or considering whether the color change is predictable from mixing. To help students: Show that color change alone is weak evidence - demonstrate both physical color mixing (food coloring) and chemical color change (with bubbles/temperature), emphasizing the need for multiple indicators. Watch for: Students who conclude chemical change from color alone without checking temperature, gas, or smell, or who don't distinguish between predictable color mixing (physical) and unexpected color change with other indicators (chemical).
A student says, “A new substance formed because the mixture got warmer.” In the investigation, students mixed 100 mL of cold water (10°C) with 100 mL of hot water (50°C). The final temperature was 30°C, and there were no bubbles, no new smell, and no solid formed. Based on the evidence, is the student’s reasoning correct?
No, the reasoning is not correct because the temperature changed due to mixing hot and cold water. The evidence does not show a reaction making heat or gas.
Yes, the reasoning is correct because any temperature change means a chemical change happened. The final temperature proves a new substance formed.
No, the reasoning is not correct because water cannot be measured in degrees Celsius. Without correct units, you cannot decide.
Yes, the reasoning is correct because hot and cold water always react together. Mixing different temperatures makes a new substance.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically connecting observations to conclusions through reasoning. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. Temperature change only counts as chemical evidence if from reaction itself, not from adding hot/cold substance. For this question, hot and cold water mixed showing predictable temperature averaging - physical change. Choice C is correct because it correctly identifies that temperature change from mixing hot and cold water is not evidence of chemical reaction. This shows the student understands must distinguish reaction-produced changes from external changes. Choice A represents a common error where students think temperature change from adding hot water is evidence of chemical reaction (it's not - must come from reaction itself). This typically happens because elementary students may not yet understand that temperature change must come from reaction itself, not external source. To help students: Use side-by-side comparison of chemical (baking soda + vinegar) vs physical (salt + water) so students see difference. Watch for: Students who think temperature change from adding hot water is evidence of chemical change.
Two groups mixed different substances in cups at room temperature (22°C). Group 1 mixed lemon juice and baking soda. Group 2 mixed sugar and water. Group 1 saw lots of bubbles and the temperature dropped to 19°C. Group 2 saw the sugar disappear, no bubbles, and the temperature stayed 22°C. Based on the data shows, which group most likely formed a new substance?
Group 1 because bubbles formed and the temperature changed without adding hot or cold. These indicators support a chemical change.
Group 2 because the sugar disappeared, which means it turned into something new. Disappearing is the strongest evidence of a chemical change.
Neither group because you cannot know without looking under a microscope. Evidence must always be microscopic to be valid.
Both groups because mixing any two substances always makes a new substance. Every mixture is a chemical change.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically evaluating whether evidence supports new substance formation. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. Temperature change only counts as chemical evidence if from reaction itself, not from adding hot/cold substance. For this question, Group 1 (lemon juice + baking soda) showed bubbles and temperature drop - chemical indicators, while Group 2 (sugar + water) showed only dissolving - physical change. Choice B is correct because it correctly identifies that Group 1's multiple indicators (bubbles + temperature change) support chemical change while Group 2's dissolving is physical. This shows the student understands to compare evidence between groups. Choice A represents a common error where students think dissolving is chemical change because substance 'disappears' (it's physical - still there in tiny pieces). This typically happens because dissolving seems so dramatic that 5th graders assume it's chemical, but substance is still present and recoverable. To help students: Use side-by-side comparison of chemical (acid + base) vs physical (sugar + water) so students see difference. Practice comparing data tables to identify which group has stronger evidence. Watch for: Students who think dissolving is chemical change. Students who don't compare evidence between groups systematically.
After mixing blue food coloring into water, the student observed: the color spread through the water, there were no bubbles, no new smell, and the temperature stayed at 23°C. Based on the observations, which conclusion is best?
No new substance formed because the food coloring just mixed and spread out. With no bubbles, smell, or temperature change, it is a physical change.
A new substance formed because the color changed from clear to blue. Any color change is always a chemical change.
No new substance formed because the water got colder from the reaction. A temperature change proves it was only physical.
A new substance formed because the water is now different and cannot be called water anymore. Any mixture is a chemical change.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically distinguishing predictable color mixing (physical) from unexpected color change (chemical). To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. For this question, food coloring spreading in water with no temperature change, no bubbles, and no new smell indicates physical change - the dye simply dispersed. Choice B is correct because it correctly identifies this as physical change, recognizing that food coloring just mixed and spread out without any chemical indicators present. This shows the student understands that predictable color mixing (adding colored substance to clear water) is different from unexpected color change (two clear liquids becoming colored). Choice A represents a common error where students think any color change is chemical change, not distinguishing between adding color (physical) and creating new color (chemical). This typically happens because students focus on the most obvious change (color) without checking for other chemical indicators. To help students: Demonstrate the difference between adding color (food coloring, paint mixing) which is physical, versus creating new color (two clear liquids becoming yellow) which suggests chemical change, emphasizing need for multiple indicators. Watch for: Students who think all color changes are chemical, students who don't check for additional evidence beyond color, or students who think any visible change means new substance formed.
After mixing 200 mL of room-temperature water (20°C) with 1 tablespoon of salt, students observed: the salt “disappeared” after stirring, there were no bubbles, and the temperature stayed 20°C. The mixture tasted salty. Based on the observations, is this a chemical change (new substance formed) or a physical change (no new substance formed)?
Chemical change, because the salt disappeared so it must have turned into something new. Disappearing is proof of a reaction.
Physical change, because the salt dissolved but is still salt mixed in the water. There were no bubbles or temperature change to show a reaction.
Chemical change, because tasting salty means a new substance formed. New tastes always mean chemical change.
Physical change, because any time you stir a mixture it becomes a new substance. Stirring causes chemical changes.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically distinguishing chemical change evidence from physical change evidence. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. Dissolving looks dramatic but is physical change because substance still present. For this question, salt dissolved in water showing no temperature change, no bubbles, still tastes salty - physical change. Choice C is correct because it correctly recognizes dissolving is physical change because salt still present and recoverable. This shows the student understands must distinguish reaction-produced changes from external changes. Choice A represents a common error where students think dissolving is chemical change because substance 'disappears' (it's physical - still there in tiny pieces). This typically happens because dissolving seems so dramatic that 5th graders assume it's chemical, but substance is still present and recoverable. To help students: Demonstrate that dissolved substances are still there by evaporating salt water to recover salt, showing dissolving is reversible (physical). Watch for: Students who think any dramatic change is chemical (including dissolving).
After mixing the substances, two students disagreed. They mixed 100 mL of water with 5 drops of blue food coloring. The color spread through the water in about 20 seconds, there were no bubbles, the temperature stayed at 21°C, and the mixture still smelled like water. Student A says, “A new substance formed because the water changed color.” Student B says, “No new substance formed because it was just mixing.” Based on the evidence, who is correct and why?
Student B is correct because the evidence shows only predictable mixing with no bubbles, no temperature change, and no new smell. These observations do not strongly support a new substance forming.
Both students are correct because the result could be chemical or physical. You can never tell from observations.
Student A is correct because the color spread quickly. Fast changes are always chemical changes.
Student A is correct because any color change proves a chemical change. The blue color could not happen without a reaction.
Explanation
This question tests a 5th grader's ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically distinguishing chemical change evidence from physical change evidence. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. For this question, food coloring spread in water with no temperature change or bubbles - physical change. Choice B is correct because it correctly distinguishes predictable color mixing (physical) from unexpected color change (chemical). This shows the student understands must distinguish reaction-produced changes from external changes. Choice A represents a common error where students conclude chemical change from only one weak observation (just color) without checking for stronger evidence. This typically happens because students may focus on most obvious change (color) and not check for more important evidence (temperature from reaction, gas produced). To help students: Show that color change alone is weak evidence (could be mixing colors), but color + temperature + gas together is strong evidence. Watch for: Students who don't check temperature or gas production, only notice color; Students who think all visible changes are chemical changes.
The evidence from this investigation is incomplete. Lila mixed 1 teaspoon of baking soda into 50 mL of lemon juice. She wrote, “It fizzed a lot,” but she did not measure temperature, did not note any smell change, and did not record how long the fizzing lasted. What additional observation would BEST help determine if a new substance formed?
Measure the temperature before and after mixing without adding hot or cold water. A temperature change from the reaction would be strong evidence of chemical change.
Measure the height of the student who did the experiment. Taller students usually get stronger reactions.
Count how many times the spoon was stirred. More stirring always causes chemical changes.
Write down the color of the cup used for mixing. The cup color helps decide if a new substance formed.
Explanation
This question tests a 5th grader's ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically identifying which observations constitute evidence of chemical change. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. Temperature change only counts as chemical evidence if from reaction itself, not from adding hot/cold substance. For this question, baking soda and lemon juice mixed showing fizzing - but incomplete without temperature. Choice A is correct because it correctly identifies temperature change without external heat as key chemical change evidence. This shows the student understands certain observations are reliable indicators of chemical change. Choice C represents a common error where students make conclusion without using evidence, just guessing. This typically happens because students may think their prediction is their conclusion rather than using actual evidence. To help students: Practice Claim-Evidence-Reasoning structure: state conclusion, cite observations, explain how observations support conclusion. Watch for: Students who confuse their prediction with their evidence-based conclusion; Students who can identify observations but can't explain WHY they indicate chemical vs. physical change.
Based on the evidence from this investigation, a student mixed 10 g of salt into 100 mL of room-temperature water (20°C) and stirred for 30 seconds. The water stayed clear, no bubbles formed, and the temperature stayed at 20°C. The salt seemed to disappear, and the water tasted salty. The student evaporated the water overnight and got salt crystals back. Is this a chemical change or a physical change, and what evidence supports it?
It is a physical change because the salt dissolved and could be recovered by evaporating the water.
It is a chemical change because the water tasted salty, which shows a new substance formed.
It is a chemical change because the salt disappeared, which means it turned into a new substance.
It is a chemical change because stirring causes reactions that cannot be reversed.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically distinguishing chemical change evidence from physical change evidence. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. For this question, salt dissolved in water showing no temperature change, no bubbles, still tastes salty - physical change, and critically, the salt was recovered by evaporation proving it's still the same substance. Choice C is correct because it correctly recognizes dissolving is physical change because salt still present and recoverable, showing the student understands that dissolving is physical not chemical. Choice A represents a common error where students think dissolving is chemical change because substance 'disappears' (it's physical - still there in tiny pieces), which typically happens because elementary students may not yet understand that dissolved substances are still present, just broken into tiny pieces too small to see. To help students: Demonstrate that dissolved substances are still there by evaporating salt water to recover salt, showing dissolving is reversible (physical), and teach explicitly that dissolving breaks substances into tiny pieces but doesn't change what they are. Watch for: Students who think any dramatic change is chemical (including dissolving) or who confuse disappearing with chemical change when the substance is just spread out in tiny pieces.
Students mixed 200 mL of room-temperature water with 2 teaspoons of salt and stirred for 1 minute. The salt “disappeared,” the water stayed clear, the temperature stayed at 21°C, and there were no bubbles or new smell. The next day, they left the salt water in a shallow dish and the water evaporated, leaving white salt crystals. Based on the evidence from this investigation, what is the best conclusion?
Not enough evidence was collected because students did not measure the mass. Without mass, you can never decide if a new substance formed.
No new substance formed because the salt dissolved and could be recovered by evaporating the water. The observations match a physical change.
A new substance formed because the salt disappeared. If you cannot see it, it must have turned into something new.
A new substance formed because crystals formed after a day. Crystals always mean a chemical change happened.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically distinguishing chemical change evidence from physical change evidence. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. Dissolving looks dramatic but is physical change because substance still present. For this question, salt dissolved in water showing no temperature change, no bubbles, still tastes salty - physical change. Choice B is correct because it correctly recognizes dissolving is physical change because salt still present and recoverable. This shows the student understands dissolving is physical not chemical. Choice A represents a common error where students think dissolving is chemical change because substance 'disappears' (it's physical - still there in tiny pieces). This typically happens because dissolving seems so dramatic that 5th graders assume it's chemical, but substance is still present and recoverable. To help students: Demonstrate that dissolved substances are still there by evaporating salt water to recover salt, showing dissolving is reversible (physical). Practice identifying which changes are reversible (physical) vs hard to reverse (chemical). Watch for: Students who think any dramatic change is chemical (including dissolving). Students who don't understand dissolving is physical because substance still present and recoverable.
Two students mixed sand and water in a jar. They observed: the sand stayed visible, most sand settled to the bottom after 2 minutes, there were no bubbles, and the temperature stayed the same. Based on the observations, what is the best conclusion?
No new substance formed because the sand and water stayed as separate parts. The mixture can be separated by pouring or filtering.
A new substance formed because the sand moved to the bottom. Movement in a jar is evidence of a chemical change.
No new substance formed because sand is not allowed to react with water. Some substances cannot be mixed at all.
A new substance formed because the water looked less clear. Any change in how clear water looks is a chemical change.
Explanation
This question tests 5th graders' ability to use evidence to determine whether mixing substances resulted in a new substance forming (NGSS 5-PS1-4), specifically distinguishing chemical change evidence from physical change evidence. To determine if a new substance formed (chemical change), students must analyze observations for key indicators: temperature change without external heat source, gas produced (bubbles, fizzing), unexpected color change, solid forming from liquids (precipitate), new smell, or inability to easily reverse. Physical changes show dissolving (substance breaks up but still there - can recover it), predictable color mixing, separation, or state changes. For this question, sand and water mixed showing no temperature change, no bubbles, sand still visible and separable - physical change. Choice B is correct because it correctly identifies that substances remaining separate and easily separable indicates physical change. This shows the student understands dissolving is physical not chemical. Choice C represents a common error where students think all visible changes are chemical changes. This typically happens because students may not realize that physical changes can look dramatic (dissolving, color mixing) but are still physical because original substances are still present. To help students: Emphasize that dissolving is physical (common misconception). Watch for: Students who don't understand dissolving is physical because substance still present and recoverable.