help Please!

[urDDS]

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wa volume of HCl is added if 20ml of 1 NaOH is titrated with 1 M HCl to produce a pH=2?

 

[klutzy1987]

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

 

[whateveryoulike]

wa volume of HCl is added if 20ml of 1 NaOH is titrated with 1 M HCl to produce a pH=2?

if you need to have a pH of 2 then you know that you need .01 mol H+ per L of solution, or .00001 mol per ml. you have to put 20ml HCL just to neutralize the solution (which then makes it 40ml total). now lets look at how much HCL you need to add to start lowering the pH.

if its 1M HCL then its .001 mol/ml (which is the units we want right now).

we need the following (x is the number of ml that we're solving for)

.00001 mol = .001x <---- the number of moles per ml
----------- -------
ml 40 + x <--- the 40 is what we already had

solving for x will tell you how much (past the initial 20ml needed to neutralize) is needed to get to pH=2. the answer is a total of 20.4ml