a. calculate the moles of reactant/products for the givens.
b. use the mole ratio in the balanced equation to calcuate the unknowns.
c. reconvert to mass.
Example: Number 3
3Cu + 8HNO3 --> 3Cu (NO3)2 + 2NO + 4H2O
given 356 grams Cu(NO3)3, or 356/187.6 moles (which is equal to 1.90 moles
given 202 grams Cu (I assume you erred on the typed problem, you meant 202 g Cu). Moles Cu: 202/63.5 =3.2 moles
a. Notice the mole ratio in the balanced equation, it is 3:3 (or 1 to 1).
So in a perfect world, you should have gotten 3.2 moles copper nitrate from the 3.2 moles Cu.
Percent yield: 1.90/3.2= you do it.
Now, on the problems with limiting reactants.
look at your moles given. Calculate the moles for the other reactant from the ratios. If you have more than needed, then the given reactant is limiting.
1. Iron oxide and carbon monoxide react according to the following equation . Identify which reactant is limiting and which is excess if 43.5 grams of Fe2O3 reacts with 43.5 grams of CO
Fe2O3 + 3CO2 --> 3CO2 + 2Fe
2. Calculate the percent yield of Carbon dioxide if 20.0 grams of it are produced when 19.5 grams of butane are burned in excess O2 according to the following equation
2C4H10 + 13O2 --> 8CO2 + 10 H2O
3. Calculate the percent yield of copper nitrate if 356 grams of it are produced when 202 grams of copper nitrate are reacted according to the following equation
3Cu + 8HNO3 --> 3Cu (NO3)2 + 2NO + 4H2O
4. When 150 grams of ZnS are burned in excess oxygen 0.685 grams of ZnO are produced according to the following equation. What is the percent yield for this reaction.
2ZnS + 3O2 --> 2ZnO + 2SO2
5. What is the actual yield in grams of oxygen if you start with 100 grams of H2O2 ? The reaction proceeds according to the following equation
2H2O2 --> 2H2O + O2
I'm don't really know how to solve any of these problems. Can you show me how to do each of these prioblems ? Please I really need help
1 answer