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    Cadet cloud edwards's Avatar
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    2016 hsc help chemistry

    How does one do Question 18 of 2016 HSC Chemistry

    Question: 40 mL of 0.10 mol L–1 NaOH is mixed with 60 mL of 0.10 mol L–1 HCl.
    What is the pH of the resulting solution?
    (A) 7.0
    (B) 1.7
    (C) 1.4
    (D) 1.2

    ANSWER IS: B

    Thanks

    Paper
    https://educationstandards.nsw.edu.a...6810f6-lHPDE.v

    Answers
    http://educationstandards.nsw.edu.au...e01834-lJl54sm
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    Senior Member jazz519's Avatar
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    Re: 2016 hsc help chemistry

    Write a chemical equation naoh + hcl ---> nacl + h2o

    Find moles of the two reactants
    n(naoh) =0.004 moles
    n(Hcl)=0.006 moles

    So hcl is in excess, thus after all the naoh reacts there is still 0.002 moles of hcl remaining

    Thus h+ concentration=0.002/0.1=0.02

    So ph=-log(0.02)=1.69
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