Water in Mechanism
Moderators: Chem_Mod, Chem_Admin
-
- Posts: 74
- Joined: Fri Sep 29, 2017 7:06 am
Water in Mechanism
If water is in one of the steps, should it be included in the equilibrium equation (K), or left out bc it is a liquid? If it is left out, does that mean it is also left out of the rate law?
Re: Water in Mechanism
Solids and liquids are not included when determining the equilibrium constant K. I'm not sure if liquids are included in the rate law though.
-
- Posts: 50
- Joined: Sat Jul 22, 2017 3:01 am
Re: Water in Mechanism
If it is the solvent, then you can leave it out of the rate law. This is because solvents are present in such high concentrations that their concentrations don't change much during the reaction.
-
- Posts: 74
- Joined: Fri Sep 29, 2017 7:06 am
Re: Water in Mechanism
Would it tell us in the problem if water is the solvent? In one problem you had to assume water was the solvent, and then later they were like "now what if there was an organic solvent instead."
-
- Posts: 31
- Joined: Thu Jul 13, 2017 3:00 am
Re: Water in Mechanism
Water is left out of the equilibrium expression because it is a liquid, and liquids have constant concentrations. Generally this means it is included as part of the equilibrium constant because it's constant anyways. The same applies for the rate constant expression.
-
- Posts: 71
- Joined: Fri Sep 29, 2017 7:04 am
- Been upvoted: 1 time
Re: Water in Mechanism
Jennifer Ho 1K wrote:Water is left out of the equilibrium expression because it is a liquid, and liquids have constant concentrations. Generally this means it is included as part of the equilibrium constant because it's constant anyways. The same applies for the rate constant expression.
This is an extremely detailed and apparently competent answer. This is where I felt water stood in regards to reaction rate laws and rate constants, however, I was never 100% sure so if Chem_Mod could come through and help?
However, it stands to reason that most times water will work as a solvent for our problems and therefore can be left out. Not to mention it's pretty consistently constant concentration, I just never thought about including it as part of the equilibrium constant.
Return to “Reaction Mechanisms, Reaction Profiles”
Who is online
Users browsing this forum: No registered users and 9 guests