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!
I GAVE you a step by step solution. Here is the question.
The half-life of a reaction was found to be inversely dependent on the concentration of the starting material. Thus, we can say that
I gave you the three possibilities. zero order, 1st order, 2nd order. (I didn't include orders higher than that because they usually don't happen.). Now, read the problem and see which answer fits the question. ",.....was found to be INVERSELY dependent on the CONCENTRATION of the STARTING MATERIAL."
Only one of those three possible answers shows the starting material in the denominator.
558.7
To determine the order of a reaction based on the relationship between the half-life and the concentration of the starting material, we can follow these steps:
1. Understand the concept of reaction order: In chemistry, the reaction order is a measure of how the rate of a reaction depends on the concentration of the reactants. It can be zero order, first order, second order, or a combination of orders.
2. Recall the definition of half-life: The half-life of a reaction is the time it takes for the concentration of a reactant to decrease by half. It is often represented by the symbol "t1/2".
3. Analyze the given information: In the question, the half-life of the reaction is stated to be inversely dependent on the concentration of the starting material.
4. Determine the relationship between half-life and concentration for different orders of reaction:
- For zero order reactions, the half-life is directly proportional to the initial concentration. Formally, t1/2 = (Ao) / 2k, where (Ao) is the initial concentration and k is the rate constant.
- For first order reactions, the half-life is inversely proportional to the initial concentration. In equation form, t1/2 = 0.693 / k.
- For second order reactions, the half-life is inversely proportional to the square of the initial concentration. The equation is t1/2 = 1 / (k * (Ao)).
5. Relate the given information to the equations: The question states that the half-life is inversely dependent on the concentration of the starting material. This means that as the concentration increases, the half-life decreases.
6. Match the given information with the equation: Looking at the equations for different orders, we can see that the only order that fits the given information is first order. In first order reactions, as the concentration increases, the half-life decreases.
7. Answer the question: Based on the above analysis, we can conclude that the reaction is first order.
So, the correct answer is b. the reaction is first order.