IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: Assi1993 on November 10, 2010, 05:17:05 pm

Title: Chemistry - Edexcel Question - A2
Post by: Assi1993 on November 10, 2010, 05:17:05 pm
hello all! =)
can some1 define Ka, pKa and pH for me :S im confused!!
Title: Re: chemistery edexcel question-A2
Post by: Deadly_king on November 11, 2010, 05:07:06 am
Quote from: Assi1993 on November 10, 2010, 05:17:05 pm
hello all! =)
can some1 define Ka,pKa and pH for me :S im confused!!

Hi Assi, it has been a long time since we last heard from you. ;)

pH
pH is a measure of the concentration of H+ ions in aqueous solutions. It is calculated as shown :
pH = - log [H+]

Acid dissociation constant Ka
The acid dissociation constant Ka is applicable to weak acids only.

It is a measure of the strength of an acid. The bigger the value of Ka, the stronger is the acid. It is calculated as shown :

Example : CH3CO2H <=> CH3CO2- + H+

Hence Ka of ethanoic acid is => Ka = [CH3CO2-][H+] / [CH3CO2H]

pKa

pKa is a measure of the strength of an acid. The smaller the value of pKa, the stronger the acid. It is calculated as shown :
pKa = - log Ka

Now, there is also Kb which is the base dissociation constant. It's similar to Ka except that it's for bases. ;)

Hope it helps :)
Title: Re: chemistery edexcel question-A2
Post by: Assi1993 on November 11, 2010, 11:17:16 am
thnxx alot DK :D
yeah!..
hw did ur exams go?
Title: Re: chemistery edexcel question-A2
Post by: Deadly_king on November 11, 2010, 12:39:56 pm
Quote from: Assi1993 on November 11, 2010, 11:17:16 am
thnxx alot DK :D
yeah!..
hw did ur exams go?

Hehe................anytime :)

Hmm..............there have good and bad. Can't say for sure :(

But I did my best ;)

How about you? How have you been doing?
Title: Re: chemistery edexcel question-A2
Post by: Assi1993 on November 11, 2010, 02:11:26 pm
im doin fine :)
and i didnt give any exam lately..but yeah trying to study :p
happy eid in advance :) what r ur eid plans insha-Allah :D
Title: Re: chemistery edexcel question-A2
Post by: Deadly_king on November 11, 2010, 02:15:55 pm
Quote from: Assi1993 on November 11, 2010, 02:11:26 pm
im doin fine :)
and i didnt give any exam lately..but yeah trying to study :p
happy eid in advance :) what r ur eid plans insha-Allah :D

Ooh........that's nice. Keep up the good work :)

Your studies are your priorities for now. ;)

Hey...........Eid Saeed to you too :)

Hmm........won't be enjoying too much since i'll be having my last exam the day after eid. ;D

What about you?

Title: Re: chemistery edexcel question-A2
Post by: Assi1993 on November 11, 2010, 02:19:41 pm
ohh .:|
which exam??
well.....i might be insha-Allah going to a nearby city-dammam..:)
and rest all is fine with u?
best of luck for ur exam..im sure u will do good
may Allah help u Ameen
Title: Re: chemistery edexcel question-A2
Post by: Deadly_king on November 11, 2010, 03:00:37 pm
Quote from: Assi1993 on November 11, 2010, 02:19:41 pm
ohh .:|
which exam??
well.....i might be insha-Allah going to a nearby city-dammam..:)
and rest all is fine with u?
best of luck for ur exam..im sure u will do good
may Allah help u Ameen

Chemistry and Biology P1 :D

Ooh......you're going to celebrate Eid there? That's nice   8)  Enjoy yourself ;D

Hmm................yeah, apart from exams everything is fine Alhamdulillah :)

Thank you, I really hope so :)

Thumma Ameen  ;)