Science Buddies: "Ask an Expert"

Hello,
We put potatos and chicken liver in Hydrogen Peroxide and recorded the tempertures. Why was the temperture change in the chicken liver greater then the potato ?

Hi,

Hydrogen peroxide(H2O2) will naturally breakdown or degrade into into water (H2O) and oxygen (O2), however this process is very slow. The cells that make up the chicken liver contain enzymes that speed up the breakdown hydrogen peroxide. These enzymes are acting as catalysts because they are speeding up the rate of a chemical reaction, in this case the breakdown of hydrogen peroxide. This is an example of an "exergonic" reaction. An exergonic reaction is a chemical reaction in which energy is released. In this case the energy is in the form of heat, which is why the temperature goes up.

Potatoes are composed of primarily carbohydrates, like starch, and do not contain as many enzymes as the chicken liver. Therefore the hydrogen peroxide does not degrade as quickly and you do not see an increase in temperature.

Another question you may have is: why do chicken liver cells contain these enzymes? Cells are naturally exposed to very small amounts of hydrogen peroxide, which is a byproduct of other chemical reactions. Hydrogen peroxide can damage cellular proteins and DNA. The cells avoid this problem by producing enzymes that degrade hydrogen peroxide before it can do any serious damage.

I hope this answers your questions.

-Dave