Question detail
A reaction has a half-life of 10 minutes. If the initial concentration of the reactant is 0.8 mol/dm³, what will be the concentration after 30 minutes?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Rate equations (A-level only)
Question
A reaction has a half-life of 10 minutes. If the initial concentration of the reactant is 0.8 mol/dm³, what will be the concentration after 30 minutes?
Answer
The concentration after 30 minutes will be 0.1 mol/dm³.
Explanation
This question tests the understanding of half-life in first-order reactions. The evidence is the half-life of 10 minutes, which indicates that the concentration halves every 10 minutes. After 30 minutes, the concentration has halved three times (0.8 → 0.4 → 0.2 → 0.1), leading to a final concentration of 0.1 mol/dm³.
Common mistake
Misunderstanding Half-Life
Students often confuse the concept of half-life with the total time taken for a reaction to complete, rather than understanding it as the time required for the concentration of a reactant to decrease by half.
To fix this, students should focus on the definition of half-life and practice calculating it from concentration-time graphs, ensuring they understand it represents a specific point in the reaction rather than the entire duration.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.