Physical Science

Mr. Stuart

ACIDS, BASES, AND PH

IonsAn ion – an atom or group of atoms that have a positive

or negative charge.Cation – an ion with a positive charge because of a loss of

electrons.Anion – an ion with a negative charge because of a gain of

electrons.

AcidsAcids are any compound that increases the number of

hydronium ions when dissolved in water.Acids ionize when dissolved in water and form hydronium

(H3O+ ions.)Acids always begin with an H atom (HCl = hydrochloric acid).

Strong Acids v. Weak AcidsStrong acids will ionize completely when dissolved in

water, meaning all the cations will dissociate with the anions.

Weak acids will not ionize completely when dissolved in water, meaning cations, anions, and whole acid molecules are in solution.

BasesBases are any compound that increases the number of

hydroxide ions when dissolved in water.Bases also ionize in water and form hydroxide ions (OH- ions)Bases always end with a hydroxide ion (NaOH = sodium

hydroxide)

Strong Bases v. Weak BasesStrong bases will ionize completely when dissolved in

water, meaning all the anions will dissociate with the cations.

Weak bases will not ionize completely when dissolved in water, meaning cations, anions, and whole base molecules are in solution.

What is pH?

pH measures the concentration of the hydronium (H3O+) or hydroxide (OH-) ions in the solution.The scale is logarithmic, meaning each level of pH is 10 times

stronger or weaker than the adjacent pH values.The pH of a solution will tell us if the solution is an acid

or a base.

The pH Scale

Neutralization ReactionsNeutralization reactions occur when an acid and a base

are mixed.Complete neutralization reactions – hydronium and hydroxide

ions combine to form water and the remaining ions form a salt.

All of the ions combine and the pH is reduced/raised to 7 (neutral pH)

Incomplete neutralization reactions – hydronium and hydroxide ions combine to form water and the remaining ions form a salt.

However, there will be a surplus of either hydroxide or hydronium ions meaning the solution will remain either slightly acidic or basic.