help with these 2 chemistry problems?

Question

1) sodium nitrate decomposes upon heating to form sodium nitrate and oxygen gas. this reaction is sometimes used to produce small quantities of oxygen in the lab. how many grams of sodium nitrate must be heated to produce 128g of oxygen?

2) calculate the mass of silver chloride, AgCl, and dihydrogen monosulfide, H2S, formed when 85.6g of silver sulfide, Ag2S, reacts with excess hydrochloric acid, HCl

if you can explain how you got your answers, that would be great. thanks so much

Answer 1

2NaNO3 -> 2NaNO2 + O2

Molar mass of NaNO3 = 85 g

Molar mass of O2 = 32 g

Grams of NaNO3 = 2*4*85 g = 680 g

2) Ag2S + 2HCl -> 2 AgCl + H2S

Molar mass of Ag2S = 248 g

Molar mass of AgCl = 143.5 g

Molar mass of H2S = 34 g

Moles of Ag2S = 0.3452

Mass of AgCl = 2*0.3452*143.5 g = 99.0724 g

Mass of H2S = 0.3452x34 g = 11.7368 g