In a laboratory, a student needs to heat a small amount of solid in a test tube. Which of the following is the correct procedure?

Correct answer

B. Place a small amount of solid in the test tube, hold it with a test tube holder, and heat it gently while moving the tube back and forth.

Principle or equation

When heating solids in a test tube, use a small amount, hold with a test tube holder, heat gently and move the tube to distribute heat, and never point the open end at yourself or others.

Why this answer is correct

Option B is correct: use a small amount to avoid overflow, hold with a test tube holder, heat gently with movement to prevent cracking or spattering. Option A is unsafe because filling completely can cause expulsion of hot material. Option C is dangerous because a sealed tube can explode. Option D is unsafe because pointing the open end at yourself risks injury from splattering.

Example

When heating copper sulfate pentahydrate, place a small amount in a dry test tube, hold with a holder, and heat gently while shaking.