pKa to Kb

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Aliya Jain 2B
Posts: 101
Joined: Wed Sep 11, 2019 12:16 am

pKa to Kb

Postby Aliya Jain 2B » Thu Jan 23, 2020 2:28 pm

im a little confused on how to convert pKa to Kb? I think theres multiple ways, but what's the easiest way to do it?

Nawal Dandachi 1G
Posts: 102
Joined: Sat Sep 28, 2019 12:16 am

Re: pKa to Kb

Postby Nawal Dandachi 1G » Thu Jan 23, 2020 2:33 pm

pKa + pKb = 14, so solve for pKb. After finding pKb, use pKb = -log(kb) to find Kb

Brittney Hun 2C
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Joined: Wed Sep 11, 2019 12:15 am

Re: pKa to Kb

Postby Brittney Hun 2C » Thu Jan 23, 2020 2:36 pm

Another way to do it is to turn the pKa into Ka first. Once you turn it into ka you can use the kw (water constant) to find the kb. Set the equation to be kb=kw/ka.

805373590
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Joined: Wed Sep 11, 2019 12:17 am

Re: pKa to Kb

Postby 805373590 » Thu Jan 23, 2020 2:55 pm

You can go from pka to ka by taking 10 to the power of negative pka and when you found ka you can easily divide 10 to the power of negative 14 by ka to get kb

Justin Seok 2A
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Joined: Sat Aug 24, 2019 12:15 am

Re: pKa to Kb

Postby Justin Seok 2A » Thu Jan 23, 2020 3:09 pm

So the simplest way would be to find Pkb using the equation 14=pka+pkb. Once you find your pkb, you can use it to find kb using 10^-pkb.

KaleenaJezycki_1I
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Re: pKa to Kb

Postby KaleenaJezycki_1I » Thu Jan 23, 2020 3:57 pm

What makes logical sense for me is to think, pka=-log(Ka), therefore Ka=10^-pka. Then we know Kw= Ka x Kb and so you should rearrange the equation so that Kw/Ka=Kb and now you have your Kb value! Make sure you take it slow and pay close attention.

AKhanna_3H
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Joined: Wed Sep 18, 2019 12:19 am

Re: pKa to Kb

Postby AKhanna_3H » Thu Jan 23, 2020 4:04 pm

pKa + pKb = pKw. Therefore pKa + pKb = 14. 14 - pKb = pKa, and 14 - pKa = pKb.

Michelle Xie 2B
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Joined: Sat Aug 17, 2019 12:18 am

Re: pKa to Kb

Postby Michelle Xie 2B » Thu Jan 23, 2020 4:17 pm

pKa + pKb is pKw, which is 14.

Kristina Rizo 2K
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Joined: Wed Sep 18, 2019 12:19 am

Re: pKa to Kb

Postby Kristina Rizo 2K » Thu Jan 23, 2020 5:51 pm

Nawal Dandachi 1G wrote:pKa + pKb = 14, so solve for pKb. After finding pKb, use pKb = -log(kb) to find Kb

I thought by doing the -log, you would get pKb? Wouldn't you need to 10^pKb to get Kb? Or did I switch it?

Leila_4G
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Joined: Sat Sep 14, 2019 12:17 am

Re: pKa to Kb

Postby Leila_4G » Thu Jan 23, 2020 7:41 pm

Also, I'm forgetting the concentration equation for pKb, can someone help me with that? Thanks!

Madeline Phan 1E
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Joined: Sat Aug 17, 2019 12:18 am

Re: pKa to Kb

Postby Madeline Phan 1E » Thu Jan 23, 2020 7:51 pm

To find pka from pkb you can do 14-pka and vice versa.

Ian Morris 3C
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Joined: Wed Sep 18, 2019 12:18 am

Re: pKa to Kb

Postby Ian Morris 3C » Mon Jan 27, 2020 2:03 am

14 minus the kPa will equal the pKb. Then Kb is equal 10 to the negative pKb.

Samuel Tzeng 1B
Posts: 103
Joined: Sat Aug 24, 2019 12:15 am

Re: pKa to Kb

Postby Samuel Tzeng 1B » Mon Jan 27, 2020 3:06 am

pKa + pKb = 14, then use pKb to solve for Kb


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