acid/base titration Q from topscore

Started by Slumber
Get help with your application

Use all the free resources available to you from SDN: articles, guides, expert advising, forums discussions, and school research.

Browse articles Compare schools My application plan Read Interview Feedback
Practice for interviews Ask an Advisor
Slumber

Slumber

Hear Me Roar!
10+ Year Member
What volume of HCl was added if 20mL of 1M NaOH is titrated with 1M HCl to produce a pH=2.

The answer is 20.4mL HCl, but the topscore explaination left me scratching my head. Can someone please explain this to me? Thanks a bucket!
 
Last edited:
Sort by date Sort by votes
I'm scratching my head too. Can you post a screenshot of the solution to help make sense of it?

There's an identical problem in 2012 DAT Destroyer #254 but I don't see how following those steps can give you 30.4mL
 
Upvote 0 Downvote
cmF said:
I'm scratching my head too. Can you post a screenshot of the solution to help make sense of it?

There's an identical problem in 2012 DAT Destroyer #254 but I don't see how following those steps can give you 30.4mL
Click to expand...

I made a mistake when posting the question. I actually put down my "wrong" answer as the TS answer. The correct answer is actually 20.4 mL

1z55442.jpg
 
Upvote 0 Downvote
Thanks for the solutions. This brings up a new question though. Why can't the destroyer method posted below work for this Topscore problem?

Q9oLADw.jpg
 
Upvote 0 Downvote
cmF said:
Thanks for the solutions. This brings up a new question though. Why can't the destroyer method posted below work for this Topscore problem?

Q9oLADw.jpg
Click to expand...

Because the destroyer problem is a strong base/weak acid titration. It follows a slight different concept that says @half eqv.pt, pH = pKa. and you basically calculate eqv.pt volume using M1V1 = M2V2 or N1V1 = N2V2, and then divide it by 2.

I think this particular problem is a bit trickier.
 
Upvote 0 Downvote
You must log in or register to reply here.