## Problem 5i.11- using molarity in place of pressure?

claudia_1h
Posts: 111
Joined: Fri Aug 09, 2019 12:16 am

### Problem 5i.11- using molarity in place of pressure?

So this problem basically asks you to calculate the reaction quotient given the amount of each substance in a container and the volume of that container. All of these substances are gases however, so don't we need to use partial pressures, not molar concentrations? The answer key just divides each number of moles by volume for each term... why is this acceptable?

Jiyoon_Hwang_2I
Posts: 101
Joined: Sat Sep 14, 2019 12:17 am

### Re: Problem 5i.11- using molarity in place of pressure?

I think you use the concentrations instead of the partial pressures because the given value of K is Kc and they are asking you for Qc so you should keep it consistent by using concentrations instead of partial pressures.

Skyllar Kuppinger 1F
Posts: 52
Joined: Thu Jul 25, 2019 12:16 am

### Re: Problem 5i.11- using molarity in place of pressure?

You can also use concentration for gases. This is called Kc (k with a subscript of c). So just make you write Kc= (insert answer) instead of just K= (insert answer)

Shail Avasthi 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

### Re: Problem 5i.11- using molarity in place of pressure?

You can either use partial pressure or concentration when calculating equilibrium for gasses.