20)Consider the following reaction.

5NaN3(s)+ NaNO3(aq) 3Na2O(s) + 8N2(g) If 2.50 g of NaNg(s) react with excess NaNO3(aq). 0.995 g of N2(g) is recovered.

What is the percent yield?

19)A 1.00-L bulb contains a sample of O2 at 25C and 1.00 atm pressure. A second 1.00-L bulb contains a sample of CH4 at 25C and 1.00 atm pressure. What is the ratio of the number of molecules of methane to the number of molecules of oxygen in each of the containers?

18

If a sample of ammonia contains (7.70x10^24) nydrogen atoms, how many moles of NH3 are present? The Avogadro constant is 6.02 x 1023 mol-1.

Type in only the numerical answer with the correct number of significant figures. Note: Your answer is assumed to be reduced to the highest power possible.