When molecules collide, for a reaction to take place, two conditions must be met. Firstly, they
must have sufficient energy to react and secondly, they must have the right orientation. This
means that the ends of the molecules that are going to react must be in contact with each other.
Raising the temperature speeds up a chemical reaction.
Which of the following could be responsible for this?
1 More collisions take place.
2 The average collision has more energy.
3 The orientation of the molecules is more favourable.

Answer:

6) D

1 – When temperature increases, molecules gain more kinetic energy, therefore they move around a lot. This increases the probability of more collisions with surrounding molecules per unit time. So 1 is correct.

2 – Since the molecules gain more kinetic energy, the probability of collisions with more activation energy will also increase. So 2 is correct.

3 – An increase in kinetic energy does not alter the orientation of molecules. So, 3 is wrong.