# 3.  What is the pH of a buffer made by mixing 1.00 L of 0.020 M benzoic acid, HC7H5O2, with 3.00 L of 0.060 M sodium benzoate, NaC7H5O2? The Ka for benzoic acid is 6.3 x 10-5

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3.  What is the pH of a buffer made by mixing 1.00 L of 0.020 M benzoic acid, HC7H5O2, with 3.00 L of 0.060 M sodium benzoate, NaC7H5O2? The Ka for benzoic acid is 6.3 x 10-5

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Step 1

Given, the molarity of benzoic acid = 0.020 M

Molarity of sodium benzoate = 0.060 M

The total volume of the solution = 1L + 3L = 4L

The Ka for benzoic acid = 6.3 x 10-5

Now, we will calculate the molarities of the buffer solution,

The molarity of benzoic acid (HC7H5O2) = 1L x 0.020 M x 1/1L x 4L = 0.0050 M

The molarity of sodium benzoate (NaC7H5O2) = 3L x 0.060 M x 1/1L x 4L = 0.045 M

The concentrations of common species at equilibrium:

Step 2

Calculate the value for hydronium ion –

Step 3

Now will calculate the pH of...

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