Question
CBSEENCH11008396

Equal volumes of three acid solutions of pH 3.4 and 5 are mixed in a vessel. What will be the H+ ion concentration in the mixture?

  • 1.11 x 10-4 M

  • 3.7 x 10-4

  • 3.7 x 10-3 M

  • 1.11 x 10-3 M

Solution

B.

3.7 x 10-4

[H]+ in mixture
[H]+ of 1st acid x its volume + [H+]
of IInd acid  x its volume + [H+] of 

equals fraction numerator IIIrd space acid space straight x space its space volume over denominator Total space volume end fraction

straight M space equals fraction numerator straight M subscript 1 straight V subscript 1 space plus straight M subscript 2 straight V subscript 2 space plus space straight M subscript 3 straight V subscript 3 over denominator straight V end fraction
Assume the volume of each solution is 1 L.
[H3O+] in solution of pH = 3 is 10-3M
[H3O+] in solution of pH = 4 is 10-4 M
[H3O+] in solution is pH is 5 is 10-5 M
Total space left square bracket straight H subscript 3 straight O to the power of plus right square bracket space equals space space fraction numerator 10 to the power of negative 3 end exponent space plus 10 to the power of negative 4 end exponent plus 10 to the power of negative 5 end exponent over denominator space 3 end fraction
space equals space 0.00037
equals 3.7 space straight x space 10 to the power of negative 4 end exponent space straight M

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