ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: ttn on September 13, 2010, 11:43:52 pm

Title: quick pH question
Post by: ttn on September 13, 2010, 11:43:52 pm: Hi, can you please help me out with this question.

50 ml of a solution of pH 2 is added to 450ml of water. What is the new pH?
Title: Re: quick pH question
Post by: sajib_mostofa on September 14, 2010, 12:18:11 am: Use $C_{1}V_{1}=C_{2}V_{2}<br />$
$C_{1}$ = 10^(-2), $V_{1}$ = 0.05, $V_{2}$ =0.5

Calculate final concentration and use log to find the ph
Title: Re: quick pH question
Post by: ttn on September 14, 2010, 12:23:34 am: oh wow, thanks.
Title: Re: quick pH question
Post by: taiga on September 14, 2010, 12:23:52 am: Well initially it is 50 ml, and after being added to 450 ml it becomes 500 ml. Hence H+ has been diluted by a factor of 10. Every pH step is a dilution by a factor of 10. Hence the pH ought to just be 3 :)
Title: Re: quick pH question
Post by: sajib_mostofa on September 14, 2010, 12:25:10 am: Just occured to me thats a good way of calculating the ph if you know both volumes :)
Title: Re: quick pH question
Post by: ttn on September 14, 2010, 12:34:39 am: Quote from: taigastyle on September 14, 2010, 12:23:52 am
Hence H+ has been diluted by a factor of 10. Every pH step is a dilution by a factor of 10. Hence the pH ought to just be 3 :)
Wow, didn't see pH like that, makes sense. Thanks. But don't you mean H3O+?
Title: Re: quick pH question
Post by: Andiio on November 07, 2010, 04:17:52 pm: Quote from: Tonez on September 14, 2010, 12:34:39 am
Quote from: taigastyle on September 14, 2010, 12:23:52 am
Hence H+ has been diluted by a factor of 10. Every pH step is a dilution by a factor of 10. Hence the pH ought to just be 3 :)
Wow, didn't see pH like that, makes sense. Thanks. But don't you mean H3O+?

H+ and H3O+ are essentially the same thing, are they not? :O
Title: Re: quick pH question
Post by: Mao on November 07, 2010, 05:34:56 pm: Quote from: Andiio on November 07, 2010, 04:17:52 pm
Quote from: Tonez on September 14, 2010, 12:34:39 am
Quote from: taigastyle on September 14, 2010, 12:23:52 am
Hence H+ has been diluted by a factor of 10. Every pH step is a dilution by a factor of 10. Hence the pH ought to just be 3 :)
Wow, didn't see pH like that, makes sense. Thanks. But don't you mean H3O+?

H+ and H3O+ are essentially the same thing, are they not? :O
yeah pretty much