A student was adding NaOH to two different acid solutions, HCl and HF, until a pH of 7 was reached in both solutions. The acids had the same initial volume, and both had an initial pH of 4.5. Which statement is true regarding the amount of NaOH added to each acid?

A. Both acids require the same amount of NaOH because they are both at the same initial pH.
B. HCl will require more NaOH because HCl is a strong acid and will have a higher initial concentration.
C. Adding NaOH will not bring the pH of either solution to pH 7.
D. HF will require more NaOH because HF is a weak acid

Question

A student was adding NaOH to two different acid solutions, HCl and HF, until a pH of 7 was reached in both solutions. The acids had the same initial volume, and both had an initial pH of 4.5. Which statement is true regarding the amount of NaOH added to each acid?

 		A.	Both acids require the same amount of NaOH because they are both at the same initial pH.
 		B.	HCl will require more NaOH because HCl is a strong acid and will have a higher initial concentration.
 		C.	Adding NaOH will not bring the pH of either solution to pH 7.
 		D.	HF will require more NaOH because HF is a weak acid

vera_ewing · Answer

@sweetburger

rvc · Answer

acid + base = salt

vera_ewing · Answer

So what do you think the answer is @rvc  ?

sweetburger · Answer

I think it might be C. not really sure.

rvc · Answer

i think C

sweetburger · Answer

Could be B though. not confident

vera_ewing · Answer

@peachpi @JFraser C?

sweetburger · Answer

I feel B could be correct as it is harder to neutralize a strong acid and it would be far easier to neutralize a weak acid with a strong base such as NaOH

anonymous · Answer

I feel like I'm missing something. Is this possible to have the same volume of a weak acid and strong acid at the same pH?

sweetburger · Answer

Yes, remember that there are different concentrations of acids so it would be possible to have a weak acid and strong acid at the same volume with the same pH.

sweetburger · Answer

Some solutions of Acids are more concentrated than others is what I am trying to get across.

anonymous · Answer

got you :)

anonymous · Answer

so then if they have the same pH they would have the same concentration. Why wouldn't they use the same amount of NaOH to neutralize?

vera_ewing · Answer

So what's the answer? C or B?

sweetburger · Answer

Well it takes more volume of highly concentrated strong base to neutralize a strong acid than it does to neutralize a weak acid of the same volume. I think.

vera_ewing · Answer

@JFraser ?

anonymous · Answer

that makes sense

vera_ewing · Answer

Well, it was D.