## Ignoring the change in equilibrium

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

### Ignoring the change in equilibrium

So for equations that don't involve acids and bases we can ignore the chage if it's less than 10^-3 but for ones with acids and bases it's if it's 10^-4?

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

### Re: Ignoring the change in equilibrium

and for the non acid equations can you still ignore the change if K is 1 * 10^-3?

joannali1027
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

### Re: Ignoring the change in equilibrium

Yes because at 1*10^-4, that is when it is appropriate to approximate since the value is very small. I think in terms of regular K values, it is that anything smaller than 10^-3 is considered small enough.

Daniella Ching 4C
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: Ignoring the change in equilibrium

The safest way (or a double check) to know whether to approximate or not is to see if the change is less than 5% of the original amount present. You can solve the problem by approximation first, then do a quick calculation to make sure that the change falls within 5%.

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

### Who is online

Users browsing this forum: No registered users and 1 guest