ICE table and X

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haileyramsey-1c
Posts: 105
Joined: Thu Jul 25, 2019 12:18 am

ICE table and X

Postby haileyramsey-1c » Mon Jan 20, 2020 5:09 pm

In some circumstances, after using values from the ICE table you eliminate the x in the denominator of the K equation but in other situations you don't. When exactly should or shouldn't you? Is there a cut off value?

Paul Hage 2G
Posts: 105
Joined: Thu Jul 25, 2019 12:17 am

Re: ICE table and X

Postby Paul Hage 2G » Mon Jan 20, 2020 5:14 pm

When the K value is less than 10^-3, it is safe to assume that the value of x will be negligible compared to the initial concentration. However, to make sure that x can be excluded from the denominator in the K expression, you can check that x is less that 5% of the initial concentration.

EMurphy_2L
Posts: 128
Joined: Sat Sep 07, 2019 12:16 am

Re: ICE table and X

Postby EMurphy_2L » Mon Jan 20, 2020 5:45 pm

this is correct, it's basically just used to save yourself time not doing the quadratic equation and assuming that a small value being subtracted in the denominator won't really change the equation. because we say it's negligible and not that it's zero, we still keep the x squared in the numerator

MAC 4G
Posts: 121
Joined: Wed Sep 18, 2019 12:16 am

Re: ICE table and X

Postby MAC 4G » Mon Jan 20, 2020 5:56 pm

To approximate you would want a K value less that 10^-3, but if you aren't sure whether or not it meets the cut off, then I suggest using the quadratic formula just to be safe.

505306205
Posts: 97
Joined: Thu Jul 25, 2019 12:15 am

Re: ICE table and X

Postby 505306205 » Mon Jan 20, 2020 5:57 pm

You eliminate x from the denominator when K is less than 0.001. This is because when K is this small, the change (x) will be less than 5% of the initial concentration.

Yiyang Jen Wang 4G
Posts: 76
Joined: Wed Nov 21, 2018 12:18 am

Re: ICE table and X

Postby Yiyang Jen Wang 4G » Mon Jan 20, 2020 7:07 pm

You can approximate when K is less than 10^-3.

Ellen Amico 2L
Posts: 101
Joined: Thu Sep 19, 2019 12:16 am

Re: ICE table and X

Postby Ellen Amico 2L » Mon Jan 20, 2020 7:08 pm

You can approximate when K is less than 10^-3 because the change in the initial concentration will be so small that x will be a negligible value.


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