Gen Chem Question (Regarding titrations)

[Pajamasam9090]

The question is how much HCL is added if 20mL solution of 1M NaOH is titrated with 1M solution of HCL to get a pH of 2.

Alright. Pretty much the only thing I get about it is that it will take 20mL of HCl to completely neutralize everything. I have seen the answer done, and it still didn't make any sense so hopefully someone here can go slowwwww and explain each step! Thanks

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[alanan84]

Check this out and let me know if it doesn't make sense...

http://forums.studentdoctor.net/showthread.php?t=646999

 

[Pajamasam9090]

So you almost want to "start" at neutral pH before you start tackling the problem.

My attempt at the problem i started like this:

2 = -log[H+] which = .01 I then knew that I would need the concentration of H+ to be .02 larger than OH-... I think maybe that's where I got confused?

I think that explanation clears it up... I would have never thought to use M1V1 = M2V2 which seems to make it easier if you think about it.

Thanks!

 

[Shinpe]

I thought that question was really shady. I got 20.4 mL but I chose 20.2 instead of none of these because I thought it was close enough or I might had made some approximations. Does anyone know if the actual DAT is shady like that?