## using mass or conc in rate laws

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

Summer de Vera 2C
Posts: 65
Joined: Fri Sep 28, 2018 12:16 am

### using mass or conc in rate laws

Hi! Just to confirm, can you either use mass (g) or concentration (M) in the rate laws if it's a sealed vessel? If so, does someone mind explaining this further?

Tuong-Minh Tran 1C
Posts: 30
Joined: Fri Sep 28, 2018 12:19 am

### Re: using mass or conc in rate laws

Rate laws typically only use concentration. If a question gives or asks for the mass of a product or reactant, then you'll have to use the molar mass and volume of the substances involved to convert between mass and concentration.

Yiting_Gong_4L
Posts: 69
Joined: Fri Sep 28, 2018 12:25 am

### Re: using mass or conc in rate laws

when working with rate laws, you should be using concentration.
given grams of a substance and volume you can solve for the M which is concentration to plug into rate laws.