Question

Am I right?

Classify the following properties of sodium metal as physical or chemical:
•Silver metallic color—physical property
•Turns gray in air—physical property
•Melts at 98º C-melting point is physical property
•Reacts explosively with chlorine gas—chemical property


Classify the following changes as physical or chemical:
•Water freezes at 0º C –physical change
•Baking soda when combined with vinegar produces bubbles—chemical change
•Mothballs gradually disappear at room temperature—physical change
•Ice cubes in a freezer get smaller with time—physical change
•Baking soda loses mass as it is heated-physical change
•Tarnishing of silver—chemical change

Answer 1

Na turns gray in air. The gray color is physical, the reaction of Na to the oxide is chemical.

Baking soda loses weight on heating due to NaHCO3 ==> Na2CO3 + H2O which is a chemical change.

Answer 2

sodium metal is insoluble in ether.
sodium metal dissovles in water to produce a gas.
Oil dissolves in gasoline and gives a homogeneous solution.
a drop of silver nitrate solution in a newborn's eye destroys the bacteria that can cause blindness.

Answer 3

How would you show that dissolving table salt is a physical change?

Answer 4

find out by urself