Use the Henderson-Hasselbalch equation to calculate the pH of a solution that is 0.140M in propanoic acid and 0.120M in potassium propanoate

This is nothing more than plug and chug

pH = pKa + log (base)/(acid)
base = propanoate
acid = propanoic acid
You must look up the value for pKa propanoic acid.

To calculate the pH of a solution using the Henderson-Hasselbalch equation, you first need to understand the components of the equation. The Henderson-Hasselbalch equation is:

pH = pKa + log ([A-]/[HA])

Where:
- pH is the measure of the acidity or alkalinity of a solution.
- pKa is the logarithmic form of the acid dissociation constant.
- [A-] is the concentration of the conjugate base.
- [HA] is the concentration of the acid.

Now, let's apply this equation to the given solution:
- The propanoic acid (HA) is the acid component with a concentration of 0.140M.
- The potassium propanoate (A-) is the conjugate base component with a concentration of 0.120M.

To use the Henderson-Hasselbalch equation, you first need to know the pKa value for the propanoic acid. The pKa can usually be found in reference books or online databases. For propanoic acid, the pKa value is approximately 4.87.

Now, substitute the values into the equation:

pH = 4.87 + log ([A-]/[HA])

pH = 4.87 + log (0.120/0.140)

Next, calculate the ratio [A-]/[HA]:

[A-]/[HA] = 0.120/0.140

[A-]/[HA] ≈ 0.857

Substitute this ratio back into the equation:

pH = 4.87 + log (0.857)

Use a calculator to find the log of 0.857:

log (0.857) ≈ -0.066

Finally, substitute this value back into the equation:

pH = 4.87 - 0.066

pH ≈ 4.804

Therefore, the pH of the solution that is 0.140M in propanoic acid and 0.120M in potassium propanoate is approximately 4.804.

Remember to always double-check your calculations and round the final answer to an appropriate number of significant figures based on the given data.