Which statement is true of a catalyst? a. it behaves as a reactant in a chemical reaction. b. it increases the temperature of a reaction. c. it decreases the concentration of the products. d. it accelerates the reaction rates of a mixture.

Correct option is D.

It accelerates the reaction rates of a mixture.

Explanation:

It is used to speed up a reaction by lowering the activation energy.Catalysis is the backbone of many industrial processes, which use chemical reactions to turn raw materials into useful products.

Types

There are two types of catalyst (1) Homogeneous (2) Heterogeneous

In a heterogeneous reaction, the catalyst is in a different phase from the reactants. In a homogeneous reaction, the catalyst is in the same phase as the reactants.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol