Lab 9: pH and Buffers

What is the [H+] solution of a solution whose pH is 9; [OH-]?

[H⁺]: 1x10⁻⁹ [OH⁻]: 1x10⁻⁵

pH equation

pH = -log[H⁺]

Buffer

A solution that minimizes changes in pH when extraneous acids or bases are added to the solution.

Buffering Capacity

The ability of a buffered solution to absorb protons or hydroxide ions without a significant change in pH; determined by the magnitudes of [HA] and [A⁻] in the solution.

NaOH ionizes completely in water. What are the [H+], [OH-], and pH of a 0.1 M solution of NaOH?

[H⁺]: 1x10⁻¹³ [OH⁻]: 1x10⁻¹ pH: 13

Strong Base

a base that completely dissociates into metal ions and hydroxide ions in aqueous solution

Strong Acid

an acid that ionizes completely in aqueous solution: release lots of hydrogen ions in solution.

Weak Acid

an acid that is only slightly ionized in aqueous solution: release little hydrogen ions in solution.

What is pH?

measure of hydrogen ion concentration

Buffer example

H2CO3, HCO3- (carbonic acid, bicarbonate) are present within the blood and serve as buffers.

Strong Acid Example

HCl (hydrochloric acid)

Potassium Phosphate Buffer

Made by mixing KH₂PO₄ (Monobasic Potassium phosphate) w/ K₂HPO₄ (dibasic potassium phosphate)

Strong Base Example

NaOH, NH³- (Sodium hydroxide, ammonia)