kleila
Forum Junior
Topics: 5
Posts: 50
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A solution of acid is prepared for cleaning surgical instruments by adding 0.5 L of 2mM HCl to 0.5 L of pure water, which has a H ion concentration of (10 up to -7) M. The initial ph of the pure water , then the ph after adding the HCl are:
A.7 , then 3
B.7 , then 4
C.7 , then 1
D.14 , then 3
E.14 , then 4
I understand that the ph of pure water (-lg[H+])=7. but then? can somebody explain?
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| vinaysaini19
Forum Junior
Topics: 12
Posts: 61
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M1V1=M2V2
so, 2mM*0.5L=xmM*1L
i.e. x=1mM So, 10 to the power -3 protons are present
therfore total protons are 10^-3 + 10^-7 which can be approx 10^-3
so final ph will be 3
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| kleila
Forum Junior
Topics: 5
Posts: 50
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oh yes , very simple...
thank you vinaysaini , i got it! 
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| nadiabarati
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but I didn't get it at all
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