BMST - Basic Math and Science Chemical Reactions and Stoichiometry Questions and Answers 4 — Questions and Answers
Question 1: What does a catalyst do in a chemical reaction?
- Increases the amount of product formed
- Lowers the activation energy without being consumed (Correct answer)
- Raises the activation energy to speed up the reaction
- Acts as a reactant that is fully consumed
Correct answer: Lowers the activation energy without being consumed
A catalyst lowers the activation energy of a reaction and is not consumed in the process.
Question 2: In the equation N₂ + 3H₂ → 2NH₃, what is the mole ratio of H₂ to NH₃?
- 1:2
- 3:2 (Correct answer)
- 2:3
- 1:1
Correct answer: 3:2
The coefficients show 3 moles of H₂ produce 2 moles of NH₃, giving a ratio of 3:2.
Question 3: Which term describes the minimum amount of reactant needed to produce a specific amount of product?
- Theoretical yield
- Percent yield
- Limiting reagent (Correct answer)
- Excess reagent
Correct answer: Limiting reagent
The limiting reagent is the reactant that is completely consumed first and determines the maximum amount of product.
Question 4: The reaction CaCO₃ → CaO + CO₂ is best classified as which type?
- Synthesis
- Decomposition (Correct answer)
- Double replacement
- Single replacement
Correct answer: Decomposition
One compound breaking into two simpler substances is the definition of a decomposition reaction.
Question 5: What is the percent yield if the theoretical yield is 50 g and the actual yield is 40 g?
- 40%
- 60%
- 80% (Correct answer)
- 90%
Correct answer: 80%
Percent yield = (actual yield / theoretical yield) × 100 = (40/50) × 100 = 80%.
Question 6: In a neutralization reaction between an acid and a base, what are the two products typically formed?
- Two salts
- Water and a salt (Correct answer)
- Two acids
- An oxide and water
Correct answer: Water and a salt
Acid-base neutralization produces a salt and water (e.g., HCl + NaOH → NaCl + H₂O).
Question 7: How many molecules are in 1 mole of any substance?
- 6.02 × 10²¹
- 6.02 × 10²³ (Correct answer)
- 3.01 × 10²³
- 1.20 × 10²⁴
Correct answer: 6.02 × 10²³
Avogadro's number states that 1 mole of any substance contains 6.02 × 10²³ particles.
BMST - Basic Math and Science Chemical Reactions and Stoichiometry Questions and Answers 4
What does a catalyst do in a chemical reaction?