## Why Ignore Liquid or Solid Volume When Calculating K

gconcha
Posts: 37
Joined: Fri Aug 09, 2019 12:16 am
Location: Sunset Village
Contact:

### Why Ignore Liquid or Solid Volume When Calculating K

Why is it that when calculating for the KP (aka the Equilibrium Constant via pressures), that we don't take into account the volume taken up by liquid or solids in the container with the gas? Since they're hard to compress, wouldn't that reduce the amount of volume available for the gases?

Rita Chen 1B
Posts: 112
Joined: Sat Jul 20, 2019 12:15 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

I think one thing is that the activity of a solid or liquid is equal to 1, so it doesn’t affect the K constant. Also in terms of solids, it is not dissolved, so would not have a concentration and I think something similar can be said with liquids as well.

Vicki Liu 2L
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

Kp is calculated using partial pressures not volume. Liquids and solids are excluded from the expression because they are available in excess so their pressures do not change before and after equilibrium.

Jack Riley 4f
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

Liquids and solids cannot be dissolved or have their pressures changed in solution so they are not factored in when calculating K.

BNgo_2L
Posts: 95
Joined: Wed Sep 11, 2019 12:17 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

Liquids and Solids don't have/have minimal changes in pressures nor concentrations, so they are typically not involved in computing the equilibrium constant.

Jamie Lee 1F
Posts: 106
Joined: Fri Aug 09, 2019 12:16 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

Liquids and solids don't necessarily dissolve in solvent, which is a main component of "concentration", which is then the focus of equilibrium calculations.

Bilal Pandit 1J
Posts: 98
Joined: Wed Sep 11, 2019 12:16 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

K is all about the concentrations, and the change in the liquid and solid-state is negligible so we can just ignore that.

RichBollini4G
Posts: 100
Joined: Wed Sep 18, 2019 12:18 am

### Re: Why Ignore Liquid or Solid Volume When Calculating K

BNgo_2L wrote:Liquids and Solids don't have/have minimal changes in pressures nor concentrations, so they are typically not involved in computing the equilibrium constant.