How to solve density problems?

Question

can anyone explain and show me steps for these problems?

thank you to all that try to answer.

2NaN3 (s) --> Na (s) + 3N2 (g)

How many grams of NaN3 are required to produce 10.0 square ft of nitrogen gas if the gas has a density of 1.25g/L?

_____________

A piece of aluminum foil 0.550 mm thick and 1.00 cm square is allowed to react with bromine to form aluminum bromide.

How many moles of aluminum were used? The density of aluminum is 2.699 g/cm3)

How many grams of aluminum bromide form, assuming that the aluminum reacts completely?

Answer 1

Sorry I suck at conversion but for a) How many L in 10sq feet then multiply by density. b) Find volume in cm3 and multiply by density. Divide answer by the molar mass and then you have the answer.

Answer 2

15

and

12,5