Evaluate Material Trade-offs Practice Test

A lab needs a spatula/scoop for transferring solid sodium hydroxide (NaOH) pellets. Requirements: must resist strong base (critical), must not contaminate samples, and should be durable. Budget is moderate.

Materials:

• Stainless steel: strong and durable; can be attacked by strong base over long exposure; moderate cost.
• Nickel alloy: excellent resistance to strong base; durable; higher cost.
• Aluminum: reacts with strong base; low cost; lightweight.

A company needs a reusable bottle for transporting concentrated vinegar (acetic acid) for cleaning. Requirements: (1) must not react with the acid (safety is non-negotiable), (2) must survive being dropped occasionally, and (3) must stay under a moderate budget.

Material options:

• Glass: very chemically inert; low reactivity; but breaks easily when dropped.
• HDPE plastic: good acid resistance; tough and drop-resistant; but can slowly absorb odors and may deform near high heat.
• Aluminum: lightweight and tough; but can corrode in acids unless coated; coating can scratch.

Which material is the best overall trade-off given the constraints?