The half-life of a reaction was found to be inversely dependent on the concentration of the starting material. Thus, we can say that

a. the reaction is zero order b. the reaction is first order c. the reaction is second order

d. the reaction starts out first order and changes to second order after one half-life.

e. the reaction starts out second order and changes to first order after one half-life.

Need some help

chemistry - DrBob222, Friday, February 17, 2012 at 10:04pm
Write these down some place where you can keep it until you can (a) derive them or (b) memorize them.
half life:
zero order is (Ao)/2a*k

order 1 is 0.693/ak

order 2 is 1/a*k*(Ao)

both a and k are constants; a is the coefficient and k is the rate contant.
(Ao) = initial concn

chemistry - elvis, Saturday, February 18, 2012 at 8:33pm
dosent answer the question?

need step by step solution and answer because i have no idea how to do this!

This is a duplicate post.

To determine the order of the reaction based on the given information, we can use the concept of half-life. The half-life of a reaction is the time it takes for the concentration of the reactant to decrease by half.

Based on the information given, the half-life of the reaction is inversely dependent on the concentration of the starting material. This means that as the concentration of the starting material decreases, the half-life of the reaction increases.

In order to relate the half-life to the order of the reaction, we can use the formulas provided:

- For a zero-order reaction, the half-life is given by (Ao)/(2a*k), where (Ao) is the initial concentration of the reactant, a is the coefficient of the reactant in the chemical equation, and k is the rate constant.

- For a first-order reaction, the half-life is given by 0.693/(a*k), where a and k have the same meanings as before.

- For a second-order reaction, the half-life is given by 1/(a*k*(Ao)).

Now, let's analyze the given options:

a. The reaction is zero-order: This cannot be the answer, as the given information states that the half-life is inversely dependent on the concentration of the starting material, not constant.

b. The reaction is first-order: This could be the answer, as the half-life being inversely dependent on the concentration of the starting material is consistent with a first-order reaction.

c. The reaction is second-order: This cannot be the answer, as the given information contradicts the half-life being directly dependent on the concentration of the starting material.

d. The reaction starts out first order and changes to second order after one half-life: This is not supported by the given information, as it specifically states that the half-life is inversely dependent on the concentration of the starting material, rather than changing after one half-life.

e. The reaction starts out second order and changes to first order after one half-life: This is not supported by the given information, as it specifically states that the half-life is inversely dependent on the concentration of the starting material, rather than changing after one half-life.

Based on the analysis, the correct answer is b. The reaction is first order. The half-life being inversely dependent on the concentration of the starting material is consistent with a first-order reaction.