Design Chemical Change Investigations Practice Test

Add vinegar to the salt water and look for bubbles; if bubbles form, conclude dissolving salt was a chemical change.

Stir the salt into water and decide it is a chemical change if the water tastes salty; do not take any measurements.

Measure the mass of an empty evaporating dish, then add the salt solution and evaporate the water gently (e.g., on a warm hot plate). Compare the mass and appearance of the recovered solid to the original salt. Independent variable: whether water is removed; dependent variable: mass/identity (appearance) of recovered solid; controls: same starting salt mass and water volume; evidence: recovery of the original solid with no new substances observed.

Heat the salt solution until it boils vigorously and record the highest temperature reached to prove a chemical reaction occurred.