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Mole Ratios and Stoichiometry 4 questions

Mole Ratios and Stoichiometry

New Regents original practice • Name: ____________________ Date: __________ Show your work for written answers.

Coefficients in a balanced equation represent relative numbers of particles and relative amounts in moles. Use the stated amounts of pure substances and assume complete reaction when asked for the theoretical amount.

Question 1

For N₂ + 3H₂ → 2NH₃, which ratio converts moles of H₂ consumed to moles of NH₃ formed?

  1. 3 mol NH₃ / 2 mol H₂
  2. 2 mol NH₃ / 3 mol H₂
  3. 2 mol H₂ / 3 mol NH₃
  4. 1 mol NH₃ / 3 mol H₂

Question 2

For 2Mg + O₂ → 2MgO, calculate the moles of O₂ needed to react with 0.600 mol Mg. Show the mole ratio.

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Question 3

For H₂ + Cl₂ → 2HCl, a student says 1.0 mol H₂ consumes 2.0 mol Cl₂. Explain the error.

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Question 4

For CaCO₃ → CaO + CO₂, how much CaCO₃ decomposed if 0.45 mol CO₂ formed and this was the only reaction?

  1. 0.23 mol
  2. 0.30 mol
  3. 0.45 mol
  4. 0.90 mol

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Hydrogen for a Fuel Cell 4 questions

Hydrogen for a Fuel Cell

Use the information below to answer questions 5–8.

In a model hydrogen fuel cell, hydrogen and oxygen react to form water. Use 2H2 + O2 → 2H2O. The table gives the amounts supplied in two independent trials. Assume each reaction runs until one reactant is used up.

TrialH2 supplied (mol)O2 supplied (mol)
A0.800.60
B0.800.30

Question 5

Calculate the moles of O₂ needed to use all the hydrogen supplied in Trial A. Show your setup.

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Question 6

Which reactant is in excess in Trial A? Use evidence from the table and the equation.

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Question 7

What is the theoretical amount of water formed in Trial B?

  1. 0.30 mol
  2. 0.40 mol
  3. 0.60 mol
  4. 0.80 mol

Question 8

A student predicts the two trials form equal amounts of water because they start with equal amounts of H₂. Explain why this prediction fails.

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