Question

The table shows the procedure for an experiment.

Step Procedure
1 Crush 5 grams of salt into a fine powder.
2 Transfer the powder to a beaker filled with 30 milliliters of liquid water.
3 Place the beaker on a hot plate and stir to dissolve the powder.
4 Boil water until all of the liquid water evaporates and the solid salt is left in the beaker.

Which best describes the change that occurred?

a
chemical change because the state of the salt changed from solid to liquid when dissolved
b
physical change because the atoms rearranged to form a new substance
c
physical change because the chemical properties of the salt and water remained the same
d
chemical change because dissolving a solid into a liquid cannot be reversed

Answer 1

c

Dissolving the salt and then evaporating the water are physical changes — the salt and water keep their chemical identities and the process is reversible (evaporation leaves the original salt).