Mole Conversions
How many moles are in 36.0 grams of water (H₂O)?
(Molar mass of H₂O = 18.0 g/mol)
Balance the equation: H₂ + O₂
→ H₂O
What is the limiting reactant if 4.0 moles of H₂ react with 2.0 moles of O₂ to form water?
4.0/2.0 = 2
Hydrogen and oxygen are both limiting reactants.
Define percent yield.
the percent ratio of the weight of the product obtained to the theoretical yield
Convert 3.50 moles of CO₂ to grams.
(Molar mass of CO₂ = 44.0 g/mol)
Balance the equation: C₃H₈ + O₂
→ CO₂ + H₂O
If 5.0 g of aluminum reacts with 10.0 g of chlorine gas, which is the limiting reactant? (Molar masses: Al = 27.0 g/mol, Cl₂ = 70.9 g/mol)
5.0/27.0 = 0.185 mol of Al
10.0/70.9 =0.141 mol of Cl2
Chlorine Gas is limiting reactant
If the theoretical yield of a reaction is 50.0 g but the actual yield is 45.0 g, what is the percent yield?
90%
How many molecules are in 2.0 moles of oxygen gas (O₂)?
(Avogadro’s number = 6.022 × 10²³ molecules/mol)
Balance the equation: Al + Cl₂
→ AlCl₃
In the reaction N₂ + 3H₂ → 2NH₃, if you start with 3.0 moles of N₂ and 8.0 moles of H₂, what is the limiting reactant?
3/1 = 9.0 mol
Limiting reactant is H2
A reaction theoretically produces 120 g of NaCl, but only 90 g is collected. What is the percent yield?
75%
Convert 1.20 × 10²⁴ molecules of NH₃ to grams.
(Molar mass of NH₃ = 17.0 g/mol)
Balance the equation: Fe₂O₃ + C
→ Fe + CO₂
A reaction between 6.0 moles of iron and 3.0 moles of oxygen forms iron(III) oxide. What is the limiting reactant? (Reaction: 4Fe + 3O₂ → 2Fe₂O₃)
6.0/3.0 = 2
The limiting reactant is oxygen
A student produces 22.5 g of CaCO₃ in an experiment, but the theoretical yield is 30.0 g. What is the percent yield?
75%
A sample contains 8.0 g of methane (CH₄). How many molecules does it contain?
(Molar mass of CH₄ = 16.0 g/mol)
Balance the equation: KClO₃
→ KCl + O₂
Given the reaction 2H₂ + O₂ → 2H₂O, if you have 10.0 g of H₂ and 10.0 g of O₂, what is the limiting reactant? (Molar masses: H₂ = 2.0 g/mol, O₂ = 32.0 g/mol)
0.3125 mol
Limiting reactant is oxygen
If a reaction between 20.0 g of reactant and an excess reagent theoretically produces 75.0 g of product, but only 60.0 g is recovered, what is the percent yield?
80%