Stoichiometric Calculations Quiz

Noah and Samuel are conducting a chemistry experiment. They are combining hydrogen gas (H₂) and oxygen (O₂) to produce water (H₂O). If they start with 2 moles of hydrogen gas, what is the mole-to-mole ratio between the hydrogen gas they started with and the water they produced, according to the balanced chemical equation 2H₂ + O₂ → 2H₂O?

• 1:1

• 3:1

• 1:2

• 2:1

Answer explanation

The balanced chemical equation 2H2 + O2 → 2H2O shows that 2 moles of hydrogen gas (H2) react to produce 2 moles of water (H2O). This means that the mole-to-mole ratio between the hydrogen gas they started with and the water they produced is 1:1, which is the correct answer.

Calculate the number of moles of oxygen gas (O₂) required to react completely with 4 moles of hydrogen gas (H₂) according to the chemical equation H₂ + O₂ → H₂O.

Answer explanation

According to the balanced chemical equation, one mole of hydrogen gas (H2) reacts with half a mole of oxygen gas (O2) to form water. Therefore, to react completely with 4 moles of hydrogen gas, we would need half of that amount in oxygen gas. So, 2 moles of oxygen gas are required.

How many grams of carbon dioxide (CO₂) are produced when 5 moles of methane (CH₄) react completely according to the balanced chemical equation CH₄ + 2O₂ → CO₂ + 2H₂O?

• 10

• 44

• 220

• 5

Calculate the mass of sodium hydroxide (NaOH) required to react completely with 25 grams of hydrochloric acid (HCl) according to the balanced chemical equation NaOH + HCl → NaCl + H₂O.

• 24.5

• 30.2

• 27.4

• 15.8

Answer explanation

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What is the limiting reagent in the reaction between 10 grams of hydrogen gas (H₂) and 20 grams of oxygen gas (O₂) according to the balanced chemical equation:
2H₂ + O₂ → 2H₂O?

watch the video if you're unsure about limiting reactants/reagents

• H₂

• H₂O

• 2H₂O

• O₂

Answer explanation

To determine the limiting reagent, first find the moles of each reactant: 10 g H2 / (2 g/mol) = 5 mol H2 and 20 g O2 / (32 g/mol) = 0.625 mol O2. According to the balanced equation, 2 moles of H2 react with 1 mole of O2. Since 0.625 mol O2 can react with 1.25 mol H2, but there are 5 mol H2 available, O2 is the limiting reagent.

Calculate the percent yield if 25 grams of carbon dioxide (CO₂) are produced in a reaction, and the theoretical yield is 30 grams.

• 90%

• 75%

• 83.33%

• 80%

How many moles of water (H₂O) are produced when 2 moles of hydrogen gas (H₂) react completely according to the balanced chemical equation 2H₂ + O₂ → 2H₂O?

Mathematical Equivalence

ON

Determine the mass of ammonia (NH₃) produced when 10 grams of nitrogen gas (N₂) react completely according to the balanced chemical equation N₂ + 3H₂ → 2NH₃.

• 60 grams

• 45 grams

• 20 grams

• 34 grams

What is the mole-to-mass ratio between carbon dioxide (CO₂) and methane (CH₄) when they react in a balanced chemical equation?

• 1:2

• 1:3

• 2:1

• 1:1

Answer explanation

The balanced chemical equation for the reaction between carbon dioxide (CO2) and methane (CH4) is CO2 + CH4 -> 2H2O + CO. This shows that the mole-to-mass ratio between CO2 and CH4 is 1:1, which is the correct answer.

Calculate the mass of oxygen gas (O₂) required to react completely with 5 grams of hydrogen gas (H₂) according to the balanced chemical equation 2H₂ + O₂ → 2H₂O is (a)   .

• 10 grams

• 7 grams

• 5 grams

• 2 grams

Answer explanation

The balanced chemical equation shows that 2 moles of H2 react with 1 mole of O2 to form 2 moles of H2O. The molar mass of H2 is 2 grams/mole and that of O2 is 32 grams/mole. So, 5 grams of H2 is 2.5 moles. To react completely with 2.5 moles of H2, we need 1.25 moles of O2, which is 40 grams. However, the closest option to this value is '10 grams'.