Question

c) For the equation (NH4)2CO3 → CO2 + H2O + NH3, if 4.01 moles of (NH4)2CO3 reacted, what is the theoretical yield of CO2? d) For the equation N2H4 + NH3 + N2, if the theoretical yield is 28.0 grams of N2, what mass in grams of N2H4, would have to react? e) For the equation FeS + HCl → FeCl2 + H2S, if 35.0g of FeS is added to 35.0g of HCI and allowed to react, what is the theoretical yield of H,S? f) Using the numbers from problem e) above, if 10.2 g of HS were obtained in the lab (actual yield), what is the percent yield?

Answer 1

c) From the equattion: moles of CO₂ = moles of (NH₄)₂CO₃ reacted = 4.01 moles

Mass of CO₂ = moles * molar mass = 4.01 * 44 = 176.44 g

d) The balanced equation is : 3 N₂H₄$\rightarrow$ 4 NH₃ + N₂

Moles of N₂ formed = mass / molar mass = 28 / 28 = 1 mol

Moles of N₂H₄ reacted = moles of N₂ * 4 = 4 moles

Mass = moles * molar mass = 4 * 32 = 128 g

e) Balanced equation : FeS + 2 HCl $\rightarrow$ FeCl₂ + H₂S

Moles of FeS = mass / molar mass = 35 / 88 = 0.398

Moles of HCl = mass / molar mass = 35 / 36.5 = 0.959

We see that FeS is the limiting reagent as HCl is present in excess

Moles of H₂S fromed = moles of FeS reacted = 0.398

Mass of H₂S = moles * molar mass = 0.398 * 34 = 13.53 g

f) % yield = mass actually formed * 100 / theoretical yield = 10.2 * 100 / 15.3 = 66.67%