# Creating a buffer out of 0.100M solutions

• JwdePhysics
In summary, the question asks which of the given mixtures would create a buffer solution using 0.100M solutions of acetic acid, sodium hydroxide, and hydrochloric acid. From the given mixtures, it is determined that 2. and 4. would not create a buffer due to an excess of strong base or acid. In order to create a buffer, both a weak acid and its conjugate base must be present, which is only seen in mixture 3. The determination for mixture 1. is unclear without further information.
JwdePhysics

## Homework Statement

The questions asks which of the following would make a buffer given that all solutions are 0.100M and you have solutions of acetic acid, sodium hydroxide, and hydrochloric acid.
1. 20.00mL of each solution is mixed.
2. 20.00mL of acetic acid and 30.00mL of NaOH are mixed
3. 30.00mL of acetic acid and 20.00mL of NaOH are mixed
4. 20.00mL of acetic acid and 20.00mL of NaOH and 10.00mL of HCL are mixed.

None necessary

## The Attempt at a Solution

So I know that 2. is wrong because once all the acetic acid and NaOH are mixed, there will be 10 mL left of a strong base which is not a buffer. I know 3 is right because 30.00mL of acetic acid added to 20.00mL of NaOH will leave 10.00mL plus some base when the NaOH reacts so that creates a buffer. However I am not sure how to solve 1 and 4 with 3 solutions each. Does anyone have any advice for determining if 1 and 4 are right?

Buffer needs both weak acid and its conjugate base to be present. Will they be present in 1. and 2.?

JwdePhysics

## 1. What is a buffer solution?

A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added. It is made up of a weak acid and its conjugate base, or a weak base and its conjugate acid.

## 2. How do you create a buffer solution from 0.100M solutions?

To create a buffer solution from 0.100M solutions, you will need to mix equal volumes of a weak acid solution and its conjugate base solution, or a weak base solution and its conjugate acid solution. The resulting solution will have a pH close to the pKa of the weak acid or base.

## 3. What is the importance of using 0.100M solutions?

0.100M solutions are commonly used in creating buffer solutions because they provide a good balance between concentration and volume. This allows for easier preparation of the buffer solution and more accurate results.

## 4. Can I use any weak acid and conjugate base, or weak base and conjugate acid, to create a buffer solution?

No, the choice of weak acid and conjugate base, or weak base and conjugate acid, is crucial in creating a buffer solution. The pKa values of the acid and base should be close to each other in order to maintain the buffer's pH range.

## 5. How do I adjust the pH of a buffer solution?

The pH of a buffer solution can be adjusted by adding small amounts of acid or base. This will not significantly change the pH of the solution due to the buffer's ability to resist changes in pH. However, adding too much acid or base can disrupt the buffer and cause a significant change in pH.

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