Acids & bases

1. Acids & Bases

2. Acids
◦ Pre-caution
◦ Many fluids we use are acids or bases however they do not injure
us.
◦ Too strong of an acid or a base can cause serious injury.
◦ Always be cautious when working with either substance.

3. Acids
◦ pH <7
◦ A substance that are soluble (dissolves) in water and increases
the hydrogen ion concentration of the solution.
◦ Taste sour and have a "stinging" feeling (like oranges, green
apples, and rhubarb)
◦ Can dissolve metals.
◦ Contribute to environmental issues like acid rain.
◦ Strong acids pH < 2

4. Acid Videos

5. Bases
◦ pH >7
◦ A substance that is soluble (dissolves) in water to produce more
hydroxyl ions (OH) than hydrogen ions (H).
◦ Taste bitter and feel slippery.
◦ An advantage to base cleaners: they do not react with metals.
The cleaners used to unclog sinks are strong bases that readily
dissolve hair and grease, but leave the pipes unscathed.
◦ Strong Base pH > 12

6. Neutral Substances
◦ Neutral Substance (pH=7)
◦ example: distilled water.

7. pH
◦ pH ("power of hydrogen")
◦ A measure of the concentration of
hydrogen ions in the solution.
◦ Measure of how acidic or basic a
substance is.
◦ Scale of 0-14; 0 is the most acidic, 14
is the most basic.
◦ A pH of 3 is 10X more acidic than a
pH of 4.
◦ A pH of 9 is 10X more basic than a pH
of 8.

8. pH
◦ To measure pH, use a pH scale or
indicators (litmus paper and universal
indicator)
◦ litmus paper: turns blue for base, red
for acid.
◦ universal indicator: turns a different
color for each number on the pH
scale.

9. Neutralization
◦ Neutralization: A base and an acid
react to form a salt and water.
◦ Acid + Base -> Salt + Water
◦ Example: HCl + NaOH -> NaCl + H20
◦ The products are less harmful than
the reactants.

10. Neutralization
◦ Strong Acid + Strong Base
= Neutral
◦ Weak Acid + Strong Base
= Basic
◦ Strong Acid + Weak Base
= Acidic
◦ Weak Acid + Weak Base
= Neutral/Acidic/Basic

11. Acid Rain
Acid Rain: Rainwater with a lower than normal pH (<5.6).
◦ "Normal" rain is slightly acidic, because it contains dissolved carbon
dioxide, and forms a weak carbonic acid.
◦ The rain becomes more acidic when water molecules react with other
gases in the air, usually sulfur dioxide and several forms of nitrogen
oxides. These gases are created by industrial factories, coal- fired
power plants, and vehicle emissions. So acid rain is actually a mixture
of weak carbonic, sulphuric, and nitric acids.
◦ Sometimes lime (calcium hydroxide) is used to neutralize lakes.