# How much NaOH I have to add to increase pH?

• Chemistry
• bluecalculator
In summary, somebody told me that the calculation for the volume of NaOH to add is wrong because I have to consider that the acid is diprotic.
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Homework Statement
How much NaOH I have to add?
Relevant Equations
No relevant equations
Hi everyone, I'm stuck in solving this problem. I have two solution of H2SO4 5M that needs two consequential pH increasing: the first from the natural pH of H2SO4 5M (around zero) to pH 2 and then from pH 2 to pH 7. The second solution from the natural pH of H2SO4 5M to pH 2 and then from pH 2 to pH 11. I would like to understand how can I calculate the volume of NaOH (let's say 5M) I have to add for each step.
at the beginning, to calculate the Volume from pH 0 to 2 I was considering this formula:

[H3O+](after adding NaOH)=(V(H2SO4)×[H2SO4](initial)−V(NaOH)added×[NaOH])/V(H2SO4)+V(NaOH)added

But somebody told me this calculation is wrong because I have to consider that H2SO4 is diprotic.

The value I used are:
[H3O+](after adding NaOH)= 10^-2
V(H2SO4)= 1L
[H2SO4](initial)= 5 M

Thank you !

Last edited:
You should take into account not only fact the acid is diprotic, but also - especially around pH 2 - that pKa2 is close to 2.

I don't see any difference between the first and the second solution.

Yes sorry..a typo. Now it's correct. Thank you, I'm going to try!

You want to get your solution to pH7? The pH of pure water is 7, you wouldn't start with sulphuric acid. That is the pH of freshly deionised water is 7, if you leave it standing around without preventing it, it will absorb CO2 from the air and decrease to about 4.5. Also 0.001 M NaOH should be pH 11 - what do you need the sulphuric acid for?

When we get this sort of question from someone sounding rather unfamiliar we can really only help (maybe) if they tell us the practical thing they are trying to achieve or overall problem to solve.

Last edited:

## 1. How does NaOH affect pH?

NaOH is a strong base that dissociates in water to form hydroxide ions (OH-). These hydroxide ions react with hydrogen ions (H+) in a solution, resulting in an increase in pH.

## 2. What is the relationship between the amount of NaOH added and the increase in pH?

The amount of NaOH added directly affects the increase in pH. The more NaOH added, the higher the concentration of hydroxide ions in the solution, leading to a larger increase in pH.

## 3. How do I calculate the amount of NaOH needed to increase pH to a specific level?

This calculation depends on the initial pH of the solution and the desired final pH. It also takes into account the volume and concentration of the solution. A basic equation, known as the Henderson-Hasselbalch equation, can be used to calculate the amount of NaOH needed.

## 4. Is there a limit to how much NaOH I can add to increase pH?

Yes, there is a limit to how much NaOH can be added before the solution becomes too basic. This limit is known as the endpoint and can be determined by using an indicator or a pH meter.

## 5. Are there any safety precautions I should take when handling NaOH?

Yes, NaOH is a caustic substance and can cause burns if it comes into contact with skin. It is important to wear protective gear, such as gloves and goggles, when handling NaOH. It is also important to carefully measure and handle the substance to avoid spills and accidents.

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