## 15.39a

$\frac{d[R]}{dt}=-k[R]^{2}; \frac{1}{[R]}=kt + \frac{1}{[R]_{0}}; t_{\frac{1}{2}}=\frac{1}{k[R]_{0}}$

Grace Ramey 2K
Posts: 57
Joined: Thu Jul 27, 2017 3:01 am

### 15.39a

For 15.39a, can someone explain why we do not have to take the "2" into account in the equation 2A ---> B + C when solving the problem?

Ozhen Atoyan 1F
Posts: 50
Joined: Thu Jul 27, 2017 3:01 am
Been upvoted: 1 time

### Re: 15.39a

Since the problem already gives the initial concentration, final concentration, and the rate constant you can just plug them into the second order reactions formula. You do not need to use the coefficient in this case. With this chapter you mostly do not need to use the coefficients unless you are trying to find a relationship between the reactants or products. An example of when you would use the coefficient is if you are trying to go from the concentration of A to B in 2A-->B+C.

Gurshaan Nagra 2F
Posts: 49
Joined: Thu Jul 27, 2017 3:01 am

### Re: 15.39a

The coefficient is not necessary in the second order formula and the question gives you the other needed values