Amount of base needed to titrate to pH 10.00

In summary, the conversation discusses a titration problem involving a diprotic acid and a strong base. By using the equation pH=-log[H+], the minimum volume of 2.00 M NaOH needed to reach a pH of 10.00 can be found. The answer is 50.0 mL, as this is the only option that allows for complete neutralization of the acid and does not exceed pH=pKa.
  • #1
Teemo
44
3

Homework Statement


A 50.0 mL sample of a 1.00 M solution of a diprotic acid
H2A (Ka1 = 1.0 × 10–6
and Ka2 = 1.0 × 10–10) is titrated
with 2.00 M NaOH. What is the minimum volume of
2.00 M NaOH needed to reach a pH of 10.00?
(A) 12.5 mL
(B) 37.5 mL
(C) 25.0 mL
(D) 50.0 mL

Homework Equations


pH=-log[H+]

The Attempt at a Solution


I believe I am missing something extremely obvious. I find that NaOH, being a strong base will completely neutralize the acid and then additional base will be required to have the pH reach 10.00. So I found moles of hydrogen, being .05*1.00.*2. I then divided by molarity of the NaOH to find volume of NaOH required to completely neutralize it, and find 50.0 mL. Now this is where I get confused. D is the highest answer, and only has enough base to neutralize the acid, not to dissociate and to increase pH.
 
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  • #2
Not all acid is neutralized at pH 10.0.

Do you know when pH=pKa?
 
  • #3
Oh wow, sorry, I'm stupid. Thanks.
 

FAQ: Amount of base needed to titrate to pH 10.00

1. How do you calculate the amount of base needed to titrate to pH 10.00?

The amount of base needed to titrate to pH 10.00 is calculated using the formula: Volume of acid x Molarity of acid = Volume of base x Molarity of base. The volume and molarity of the acid are known, while the molarity of the base can be determined based on the desired pH of 10.00.

2. Can you use any type of base for titrating to pH 10.00?

Yes, any type of base can be used for titrating to pH 10.00. However, the strength and concentration of the base will affect the amount needed to reach pH 10.00.

3. Why is pH 10.00 chosen for titration?

pH 10.00 is commonly chosen for titration because it is a basic pH that is easily measurable and allows for a clear endpoint to be reached. Additionally, many substances have a pKa value near 10.00, making it a suitable pH for titration.

4. How does the starting pH of the acid affect the amount of base needed to titrate to pH 10.00?

The starting pH of the acid does not directly affect the amount of base needed to titrate to pH 10.00. However, a stronger acid (lower pH) will require a larger amount of base to reach pH 10.00 compared to a weaker acid (higher pH).

5. Is there a limit to the amount of base needed to titrate to pH 10.00?

There is no limit to the amount of base needed to titrate to pH 10.00. The amount required will depend on the strength and concentration of the acid being titrated, as well as the strength and concentration of the base being used.

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