Question

Vinegar is a chemical used in cooking, cleaning and other common experiences. A 0.1 M solution of vinegar in water has a [H+] of about 1.3 × 10–3. (You may prefer to think of the hydronium ion concentration, [H3O+], as 1.3 × 10–3.)

A. Write the formula for the calculation of pH, and then show each step as you calculate the pH of a 0.1 M solution of vinegar.

B. Is vinegar an acid or a base? Explain how you know.

Answer 1

Answer: a) pH of a 0.1 M vinegar solution is 2.9

b) It is an acid as pH is less than 7

Step-by-step explanation:

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

Acids have pH ranging from 1 to 6.9, bases have pH ranging from 7.1 to 14 and neutral solutions have pH equal to 7.

As vinegar is a weak acid, its dissociation is represented as;

`CH_3COOH\rightleftharpoons H^+CH-3COO^-`

cM 0 0

`c-c\alpha`
`c\alpha`
`c\alpha`

So dissociation constant will be:

`K_a=((c\alpha)^(2))/(c-c\alpha)`

Give c= 0.1 M

`[H^+]=c* \alpha`

`[H^+]=0.1* \alpha`

`1.3* 10^(-3)=0.1* \alpha`

`\alpha=0.013`

Also
`pH=-log[H^+]`

`pH=-log[1.3* 10^(-3)]=2.9`

Thus pH of a 0.1 M vinegar solution is 2.9

As pH is less than 7, it is an acid.