The half life of a first order reaction
Correct answer: C. is constant and independent of the initial concentration
- A. doubles as the reaction proceeds
- B. depends on the initial concentration
- C. is constant and independent of the initial concentration
- D. is always one second
Explanation
For first order kinetics the time taken for the concentration to fall by half is fixed, so successive halvings take equal times, and this is precisely why radioactive decay is described by a half life. The relationship is half life equals 0.693 divided by k. For zero and second order reactions the half life does depend on the starting concentration.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Rate Constant
The rate constant, k, connects reaction rate with reactant concentrations in a rate law and has a value fixed for a particular reaction at a given temperature. Questions involve determining k from rate data, identifying its units for different reaction orders, and applying the Arrhenius equation to temperature changes.
Practise Reaction Kinetics
573 free Reaction Kinetics MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Rate Constant questions
The value of the rate constant k for a given reaction changes when
The units of the rate constant k for a first order reaction are
The Arrhenius equation shows that the rate constant increases when
Final equation for the representation of rate of reaction in term of concentration is called
Ostwald's dilution law applicable to:
Rate of reaction when concentration of reactants are taken as unity is called_________________?