Experiment 2: Buffer Solution and pH

Water

~70% of human body, universal solvent.

Biochemical Reactions

Processes like metabolism and respiration occur in water.

pH

Measures hydrogen ion concentration in a solution.

pH Scale

Ranges from 0 (acidic) to 14 (basic).

pH Change

1 unit change = 10x change in [H⁺].

Buffer Capacity

Ability to maintain stable pH with added acids/bases.

Conjugate Base

Weak acid's counterpart that neutralizes added H⁺.

Ideal Buffer Ratio

1:1 ratio of acid to conjugate base.

pKa

pH at which acid and conjugate base concentrations are equal.

Acetate Buffer

Mixture of acetic acid and sodium acetate.

Buffer Components

Weak acid and its conjugate base or vice versa.

Neutralization Reaction

Conjugate base neutralizes added H⁺ from acids.

Acetic Acid

Weak acid component of acetate buffer.

Sodium Acetate

Conjugate base in acetate buffer solution.

pH Meter

Device providing precise pH measurements.

pH Paper

Approximate pH readings, rounded to 0.5.

Distilled Water

Should be boiled to remove dissolved gases.

Carbonic Acid

Forms from CO₂ in water, lowers pH.

Buffering Agents

Substances that stabilize pH in solutions.

Acidic Solutions

Soft drinks, vinegar, and pineapple juice examples.

Basic Solutions

Toothpaste neutralizes mouth acids, slightly basic.

Buffering System Strength

Stronger systems show smaller pH changes.

Homeostasis

Cells regulate pH tightly for biological function.

Buffering Factors

Concentration and acid-to-base ratio affect capacity.