A buffer solution contains 0.496 M KHCO3 and 0.340 M K2CO3. If 0.0585 moles of potassium hydroxide are added to 250. mL of this buffer, what

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A buffer solution contains 0.496 M KHCO3 and 0.340 M K2CO3. If 0.0585 moles of potassium hydroxide are added to 250. mL of this buffer, what is the pH of the resulting solution

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Calantha 4 years 2021-07-22T05:26:59+00:00 1 Answers 14 views 0

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  1. Bo
    0
    2021-07-22T05:28:25+00:00
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    Answer:

    pH = 10.9

    Explanation:

    Hello there!

    In this case, according to the given information, it turns out possible for us to say that the undergoing reaction between this buffer and OH⁻ promotes the formation of more CO₃²⁻ because it acts as the base, we can do the following:

    n_{CO_3^{2-}}=0.34mol/L*0.250L+0.0585mol=0.1435mol\\\\n_{HCO_3^{-}}=0.34mol/L*0.250L-0.0585mol=0.0265mol

    The resulting concentrations are:

    [CO_3^{2-}]=\frac{0.1435mol}{0.25L}=0.574M \\

    [HCO_3^{-}]=\frac{0.0265mol}{0.25L}=0.106M

    Thus, since the pKa of this buffer system is 10.2, the change in the pH would be:

    pH=10.2+log(\frac{0.574M}{0.106M} )\\\\pH=10.9

    Which makes sense since basic OH⁻ ions were added.

    Regards!

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