1. use the collision theory of reaction rates to explain the relationship between the temperature and the rate of a chemical reaction.
2. iodine is used as a catalyst in the decomposition of hydrogen peroxide. how is the concentration of the iodine effected by the reaction?

1. Temperature increase, rate increases.

2 It's not affected. Stands constant.

Explanation:

1. In any chemistry reactions, the rate depends on the capacity of the molecules to collide, these collisions will be major when the reagents have enough kinetic energy to move around and interact between them. The frequency of these collisions is affected by different variables such as temperature.

Temperature is equal to energy, so if to reactions are supplied by external energy like thermic energy, the molecules will move faster, and the collides can be more frequent when the temperature increases.

Collisions theory says that for a reaction occurs is necessary that all the molecules who are participating have a internal energy who provides an effective collision, otherwise, without the energy necessary will not bring about chemical change.

So a collision only will effective if the species has a minimum value of internal energy necessary, this is named activation energy of the reaction. So the temperature can provide the energy necessary to move faster and collide with the activation energy needed to bring about chemical changes. And this way increase the rate of the chemicl reaction.

2. A catalyst is a substance who is added to a reaction but has no chemical changes while the reactions occur. A catalyst is used to help the reactants to reach the activation energy and make the process faster, it means that the catalyst increases the rate of the chemical changes.

But a characteristic of this molecules, when are used as a catalyst is that it does not intervene in the chemical changes of any product or reagent, and for these reasons, the concentration of the catalyst is always constant, even when the reactions finish.