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Thread: Buffer solution question

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    Buffer solution question

    Can someone please help with this question, and show me how to do it?

    Solution C is made by mixing 57.9 mL of 0.16 M ammonium chloride (NH4Cl) with 60.4 mL of 0.26 M ammonia solution. pKa (NH4+) = 9.24
    (a) Calculate the pH of Solution C.
    (b)Calculate the pH of the buffer Solution C if 0.13 g of NaOH (molar mass = 40.0 g/mol) is added (assuming no change in volume).

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    Re: Buffer solution question

    First you find the concentration of nh4cl and nh3 which is done by converting the amount into litres x by M/the sum of the amounts in litres
    so its 0.0579x0.16/0.0579+0.0604. You do this with nh3 as well then the pH is 9.24+log(nh3/nh4)

    second part find the moles which is mass/molar mass then divide the moles by the sum of the amount in litres
    Youll get a value
    the concentration for nh4 minus this value=x
    the concentration for nh3 plus this value=y

    then the ph is 9.24 + log(y/x)

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    Re: Buffer solution question

    so would the answer be 9.82?

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    Re: Buffer solution question

    Thanks so much got it right ))))))

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    Re: Buffer solution question

    Hi, I still confused about part (b) , could u plz show me the full answer? That will be helpful.
    Cheers.

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