- Basic Math and Science Chemical Reactions and Stoichiometry Questions and Answers Flashcards

In the reaction 2H₂ + O₂ → 2H₂O, how many moles of water are produced from 4 moles of H₂?

Answer: 4 moles

The molar ratio of H₂ to H₂O is 1:1, so 4 moles of H₂ produces 4 moles of H₂O.

Which type of chemical reaction involves a single compound breaking down into two or more simpler substances?

Answer: Decomposition

Decomposition reactions break one compound into two or more simpler substances (e.g., 2H₂O → 2H₂ + O₂).

What is the molar mass of glucose (C₆H₁₂O₆)?

Answer: 180 g/mol

Molar mass = 6(12) + 12(1) + 6(16) = 72 + 12 + 96 = 180 g/mol.

In a double replacement reaction between NaCl and AgNO₃, which precipitate forms?

Answer: AgCl

AgCl is insoluble in water and precipitates out of solution in this double replacement reaction.

How many grams of CO₂ (molar mass 44 g/mol) are produced when 0.5 moles of CO₂ are generated?

Answer: 22 g

Mass = moles × molar mass = 0.5 mol × 44 g/mol = 22 g.

Which of the following is an example of a combustion reaction?

Answer: CH₄ + 2O₂ → CO₂ + 2H₂O

Combustion reactions involve a hydrocarbon reacting with oxygen to produce CO₂ and H₂O.

If you have 90 g of water (molar mass 18 g/mol), how many moles of water do you have?

Answer: 5 moles

Moles = mass / molar mass = 90 g ÷ 18 g/mol = 5 moles.