Question

1. Explain what is in a buffer. Discuss the function of a buffer. How will pH change when small amounts of acids or bases are added to the buffer solution? 2. Cooks use baking soda to make cakes light and fluffy. You might have used baking soda yourself. Baking soda is NaHCO3. A 0.1 M solution of baking soda in water has a [H+] of about 4.0 × 10–9. (You may prefer to think of the hydronium ion concentration, [H3O+], as 4.0 × 10–9.) 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 baking soda. 3. Before tackling this problem, be sure you know how to find the antilog of a number using a scientific calculator. A solution has a pH of 5.4. Write the formula you will use to calculate the [H+] and then show all your work leading to the determination of [H+].

Answer 1

Answer:

(1) See below, (2) About 8.4 pH, (3) About 3.981 * 10⁻⁶ mol dm⁻³

Explanation:

1. A buffer is a solution that resist pH when adding a basic or acidic compound. It's purpose is to neutralize added acids and bases.

2. Remember that the formula for pH is -log [H+]. We have a 0.1 M solution of baking soda in water with [H+] of about 4.0 × 10⁻⁹. Therefore we can calculate the pH as follows...

pH = -log (4.0 × 10⁻⁹)

pH = -(-8.39794...) = (About) 8.4 pH of 0.1 M of baking soda

3. This question has a similar set up...

pH = -log [H+]

[H+] = inverse of log^- pH

[H+] = 10^-5.4 = (About) 3.981 $*$ 10⁻⁶