Question detail

For Limiting reactants (HT only), which option best supports this Unit 4.3 objective: (HT only) Use balanced equations to identify which reactant limits product formation. (WS 4.1)?

Try the question, check the answer, then read the explanation to understand the curriculum point.

Show answer Topic hub Objective page

At a glance

MCQ

Type

practice

Style

Topic

Use of amount of substance in relation to masses of pure substances

Question

A. The reactant that is completely used up
B. The reactant that is present in excess
C. The reactant that produces the most product
D. The reactant that is the most expensive

Answer

The correct option is The reactant that is completely used up.

Explanation

The correct option is The reactant that is completely used up. The reactant that is completely used up is correct because it directly supports the approved learning objective to (HT only) Use balanced equations to identify which reactant limits product formation. (WS 4.1). The reasoning belongs to Limiting reactants (HT only) within Use of amount of substance in relation to masses of pure substances, so it should not be confused with nearby quantitative ideas such as mass, moles, concentration, yield, atom economy, or gas volume unless those are named in the objective. Use the focus term HT only to keep the answer aligned with AQA GCSE Chemistry 8462 Unit 4.3. The other options are weaker because they either use the wrong formula, the wrong unit, a vague relationship, or the wrong quantitative context.

Common mistake

Identifying Limiting Reactants

Students often confuse the limiting reactant with the reactant present in the smallest amount by mass, rather than by moles.

To correctly identify the limiting reactant, convert the masses of all reactants to moles using their relative formula masses, then compare the mole ratios from the balanced equation. Keep the correction anchored to Limiting reactants (HT only); check formula, substitution, calculation, final answer, and unit where relevant.

Related flashcards

Flashcard 1 of 5

Press Space to flip, arrows to move