## negligible rule [ENDORSED]

Jasmine Botello 2F
Posts: 67
Joined: Fri Sep 29, 2017 7:04 am

### negligible rule

So when K is small enough, then X can be negligible. Does this apply only to weak acids and bases or any type of reaction?

Chem_Mod
Posts: 18180
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 428 times

### Re: negligible rule  [ENDORSED]

This applies to any equilibrium reaction problem that involves an ICE table process to solve. However, you must also consider your initial concentrations or partial pressures. It is actually the % dissociation of an equilibrium reaction being under 5% which allows you to make the negligible x assumption.

Ethan Vuong 3G
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

### Re: negligible rule

if we are given an equilibrium constant on a question, is that a good indicator that we are calculating a weak base or acid and therefore eliminate the x?

Scott Chin_1E
Posts: 55
Joined: Sat Jul 22, 2017 3:00 am

### Re: negligible rule

I think first looking at the reactants and products of the problem would be a good indication for whether the problem is a weak acid/base question, especially if they only give you K instead of $K_{A}$ or $K_{B}$.

If they give you $K_{A}$ or $K_{B}$, I think its safe to assume that you are working with weak acids/bases especially since strong acids do not require equilibrium constants because they dissociate fully.

Return to “Calculating pH or pOH for Strong & Weak Acids & Bases”

### Who is online

Users browsing this forum: No registered users and 2 guests