# In terms of collision theory, why do fridges keep food fresher for longer?

Food cam go off due to different chemicals reacting with, or colliding with other molecules, in the food. Molecules have to collide with a minimum amount of energy, the activation energy or ${E}_{a}$. The lower the temperature, the less energy the molecules have, and the slower they therefore go. A fridge provides quite low temperatures, meaning fewer molecules have ${E}_{a}$ or higher. As there are fewer molecules to create a reaction, the food is kept fresher.