1. Acids & Bases

2. Acids
Definition: substances that release hydrogen ions (H+) when mixed in water
General formula: HA
H is hydrogen
A is an anion (non-metal or polyatomic ion)
For example: HCl(aq), H2SO4(aq)

4. Physical Properties of Acids
Sour tasting (e.g. lemon juice)
Wet to the touch when in solution
Water soluble
Good conductors of electricity, therefore electrolytes

5. Chemical Properties of Acids
React with metals to produce hydrogen gas
Corrosive
Make chemical indicators change colour
React with bases to produce neutral solution

6. Bases
Definition: substances that release hydroxide ions (OH-) when mixed in water, also called alkaline
General Formula: BOH
OH is the “hydroxide ion”
B is a metal (cation)
For example: NaOH(aq)

8. Physical Properties of Bases
Bitter tasting (e.g. tonic water)
Slippery to the touch when in solution
Water soluble
Good conductors of electricity, therefore electrolytes

9. Chemical Properties of Bases
Do not react with metals to produce a gas
Corrosive
Make chemical indicators change colour
React with acids to produce a neutral solution

10. Chemical Indicators
Are solutions that turn different colours in acids and bases
Can be either natural or synthetic

11. Chemical Indicators Indicator ACID NEUTRAL BASE Litmus paper
Phenolphthalein
Bromthymol blue

12. pH Scale
A numeric scale used to show how acidic or basic a solution is
pH stands for “power of hydrogen”

13. The pH Scale Each step on the pH scale is 10 times difference
E.g. a solution with a pH of 3 is 10 times more acidic than a solutions with a pH of 4
E.g. a solution with a pH of 13 is 10 times more basic than a solution with a pH of 12
Practice: How much more acidic is lemon juice (pH 2) than water (pH 7)?

14. Neutralization Reactions
A type of double displacement reaction
e.g. HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
A salt is an ionic compound produced by the reaction of an acid plus a base