Physical Science Honors Video Link  Click HERE Acids, Bases, and pH Physical Science Honors Video Link  Click HERE

Questions (NOTES) you will answer in your THROUGH: Define acid. Explain the difference between strong and weak acids. Define base. What does pH measure? Explain how pH is used to determine whether a substance is an acid or a base. Give 3 specific examples of common substances and their corresponding pH. Explain how we use pH to determine whether or not a neutralization reaction is complete.

Ions An 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.

Acids Acids are compounds that increase the number of hydronium (H3O+) 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 Acids Strong 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.

Bases Bases 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 Bases Strong 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 Reactions Neutralization 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.