I’m doing revision questions and do not know how I would do these gas law questions

Question

2. The inflation of an air bag during a car crash is due to production of nitrogen gas, N2(g), by
the following reaction:
2NaN3(s) → 2Na(s) + 3N2(g)

a) What volume of N2 is produced when 120 g of NaN3 is decomposed during a car crash
at SATP.

b) Quicklime, CaO, is produced by the thermal decomposition of calcium carbonate,
CaCO3. Calculate the volume of CO2 produced from the decomposition of 1.5 kg CaCO3
at SATP by the reaction:
CaCO3(s) → CaO(s) + CO2(g) (3 marks)
The molar volume of an ideal gas at SATP is 24.8 dm3 mol-1

 

Answer 1

a)  Look at the balanced equation.  You notice that 2 moles NaN3 produce 3 moles N2 gas.  This is now a problem in stoichiometry.  Convert the 120 g of NaN3 to moles.  120 g x 1 mole/65 g = 1.85 moles 

Now find moles N2 gas.  1.85 moles NaN3 x 3 moles N2/2 moles NaN3 = 2.77 moles N2 gas

Convert 2.77 moles N2 gas to volume using 24.8 liters/mole

 

b) Again, look at the balanced equation and note that 1 moles CaCO3 produces 1 moles CO2 gas.  Do as in the first problem. Convert 1.5 kg CaCO3 to moles, and then to moles of CO2 (1:1 mole ratio).  From moles of CO2, find the volume using the conversion of 28.4 L/mole.