9701 MCQ Solution 52

9701 MCQ Solution 52:

Question 52: [Physical > Reaction Kinetics]

It is often said that the rate of a typical reaction is roughly doubled by raising the temperature by 10 °C.

What explains this observation?

A   Raising the temperature by 10 °C doubles the average energy of each molecule.

B   Raising the temperature by 10 °C doubles the average velocity of the molecules.

C   Raising the temperature by 10 °C doubles the number of molecular collisions in a given time.

D  Raising the temperature by 10 °C doubles the number of molecules having more than a certain minimum energy

Reference: Past Exam Paper -June 2003 Paper 1 Q12

Solution 52:

Answer: D.

A cannot be answer because indeed the temperature increases the average energy of molecules but not for each molecules , there will always be some molecules who won’t show an increase in energy

B cannot be answer because again indeed the temperature increases the average energy of molecules therefore molecules velocity will increase but the average velocity of molecules isn’t doubled by raising the temperature by 10 °C it just increases but not doesn’t double.

C cannot be answer because again raising the temperature by 10 °C  doesn’t double the average velocity of molecules or double the average energy or double the collision it just increase it.

D is the answer because it says the number of molecules having more than the activation energy is doubled therefore the reaction is doubled this therefore is a better answer because the molecules themselves have energy > activation energy are doubled therefore the rate of reaction is doubled.