Equal volumes of two solutions pH=2 and pH=4 are mixed together.Calculate the pH of the resulting solution?

[H+] for solution with pH = 2 is 10-2 M
[H+] for solution with pH = 4 is 10-4 M

Since, equal volumes of the given solutions are mixed; concentration will be halved.
Therefore,
[H+] =10-2 +10-42         =10-2 (1+10-2)2         =1.01 x 10-22         =0.505 x 10-2 M

pH = -log[H+]       = -log (0.505 x 10-2)       =2.29        =2.3 

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let x be the vol. of both sol.

M1V1 +M2V2=Mnet Vnet

10-2 X x +10-4 X x= Mnet 2x

x(10-2 + 10-4) =Mnet 2x

10-2+10-4/2 = Mnet

Mnet= 5.05 X 10-3

now taking -log ans will come 2.2967

pH=2.2967

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