Math in chemistry

Front

What is the balanced equation for the decomposition of potassium chlorate (KClO₃)?

Back

2KClO₃ → 2KCl + 3O₂ + energy.

Front

How do you calculate the percent by mass of a solute in a solution?

Back

Percent by mass = (mass of solute / total mass of solution) × 100.

Front

What is the formula mass of C₉H₁₁NO₂?

Back

Formula mass = 9(12 u) + 11(1 u) + 1(14 u) + 2(16 u) = 165 u.

Front

Which compound has the greatest percent composition by mass of sulfur: MgS, SrS, BaS, or CaS?

Back

MgS has the greatest percent composition by mass of sulfur.

Front

How do you find the number of moles in a sample?

Back

Number of moles = mass (g) / molar mass (g/mol).

Front

What is the molar mass of MgCO₃?

Back

Molar mass = 24.3 (Mg) + 12.0 (C) + 3(16.0) (O) = 84.3 g/mol.

Front

If 24.51 grams of KClO₃ produces 9.60 grams of O₂, how much KCl is produced?

Back

14.91 grams of KCl are produced.

Front

What is the total mass of a solution containing 25 grams of KNO₃ in 200 grams of H₂O?

Back

Total mass = 25 g + 200 g = 225 g.

Front

How do you determine the limiting reactant in a chemical reaction?

Back

Compare the mole ratio of reactants used in the balanced equation to the moles available.

Front

What is the significance of the coefficients in a balanced chemical equation?

Back

Coefficients indicate the relative number of moles of each substance involved in the reaction.