Help with hydrogen peroxide?

HELP ME PLEASE!! Sand, Hydrogen Peroxide, Liver, Potato, and Chemicals?

• Okay, now I don't need really specific and scientific answers for this, but all of these have something to do with catalysts and enzymes, or SOMETHING! So could some people please answer these questions for me? 1. Why is there no reaction when sand is added to hydrogen peroxide? 2. why was there a fast reaction when liver was added to hydrogen peroxide? 3. why was the reaction moderate when potato (plant tissue) was added to the hydrogen peroxide? 4. why was there a moderate reaction when manganese dioxide powder was added to the hydrogen peroxide? 5. Why does the liver react twice when you put it in hydrogen peroxide twice? 6. what does heat do to the hydrogen peroxide molecules? and why would this speed up the reaction?

• Answer:

  1.Sand does not contain any enzymes or catalysts for the decomposition of peroxide 2. Liver contains high amounts of an enzyme called catalase which speeds up the reaction. 3. Potato contains low amounts of catalase. 4. Manganese dioxide acts as a catalyst, lowering the activation energy for this reaction. 5. The enzyme is still active and present in the liver sample. It can be used over again. 6. Molecules have higher kinetic energy and can collide with each other more frequently, which speeds up the rate of reaction.