Name the property that each change depends on. Then classify the property as either chemical or physical.

Question

a) You separate a mixture of gravel and road salt by adding water to it

b) Carbon dioxide gas freezes at a temperature of -78C

Answer 1

physical and physical
Adding water to salt and gravel just dissolves the salt. However, the salt is still salt and the gravel still gravel so no reaction took place.

Same thing with CO2. Water freezes at zero C and boils at 100 C BUT whether it is in the form of solid ice, liquid water, or water vapor (steam) it still is H2O. So physical.