Titration? would you explain this problem?

[Dencology]

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what volume of HCl was added to 20 mL of 1M NaOH is titrated with 1M HCl to produce a pH=2?

i just don't get this problem. ans. is 20.4mL

 

[doc toothache]

http://forums.studentdoctor.net/showthread.php?t=574267

 

[Dencology]

hey, there are some confusing statements out there. if you don't mind, can you let me know how they got 0.01 and then 20.04?

 

[doc toothache]

what volume of HCl was added to 20 mL of 1M NaOH is titrated with 1M HCl to produce a pH=2?

i just don't get this problem. ans. is 20.4mL

It takes 20 ml of 1M NaOH to neutralize 20 ml of HCl for a total volume of 40 ml of solution (pH 7). The question then becomes what volume of 1 M HCl is needed to obtain 40 ml of 0.01M solution.

M1V1=M2V2
(1)V1= (0.01)(40)
V1= 0.4

Total volume = 20 + 0.4 = 20.4