Chemical Calculations

When does a chemical reaction stop?

• when the laboratory closes

• when the excess reactant is used up

• when the limiting reactant is used up

• chemical reactions never stop

Fe + S → FeS

0.8 moles of Fe are allowed to react an excess of S. What is the mass of FeS produced?

(A_r of Fe = 56, A_r of S = 32)

• 25.6 g

• 44.8 g

• 70.4 g

• 88 g

2CO + O₂ → 2CO₂

What is the mass of CO₂ produced by reacting 2 moles of O₂ with an excess of CO?

(A_r of C = 12, A_r of O = 16)

• 22 g

• 44 g

• 88 g

• 176 g

2H₂ + O₂ → 2H₂O

How many moles of water can be made from 100 g of hydrogen?

(A_r of H = 1, A_r of O = 16)

• 25 mol

• 50 mol

• 100 mol

• 200 mol

2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

What is the mass of C₂H₆ used to produce 2 moles of CO₂?

(A_r of C = 12, A_r of H = 1, A_r of O = 16)

• 2 g

• 30 g

• 60 g

• 120 g

CH₄ + 2O₂ → CO₂ + 2H₂O

24 g of CH₄ will produce how many grams of CO₂?

(A_r of C = 12, A_r of H = 1, A_r of O = 16)

• 15 g

• 24 g

• 44 g

• 66 g

Zn + 2HCl → ZnCl​₂ ​​+ H​₂​​

When 14.6 g of HCl is used, what is the mass of H₂ produced?

(A_r of H = 1, A_r of Cl = 35.5)

• 0.2 g

• 0.4 g

• 0.8 g

• 7.3 g

2NaClO₃ → 2NaCl + 3O₂

What is the mass of O₂ produced from 213 g of NaClO₃?

(A_r of Na = 23, A_r of Cl = 35.5, A_r of O = 16)

• 48 g

• 96 g

• 213 g

• 319.5 g

2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂

What is the mass of aluminum sulfate formed if 147 g of sulfuric acid completely reacted with aluminum?

(A_r of Al = 27, A_r of H = 1, A_r of S =32, A_r of O = 16)

• 49 g

• 98 g

• 342 g

• 513 g

CuCl₂ + 2NaOH → Cu(OH)₂ + 2NaCl

After adding an excess of aqueous NaOH to 54 g of aqueous CuCl₂, what is the mass of Cu(OH)₂ obtained?

(A_r of Cu = 64, A_r of Cl = 35.5, A_r of Na = 23, A_r of O = 16, A_r of H = 1)

• 39.2 g

• 54 g

• 98 g

• 108 g