1. Acids
and Salts
Bases

2. What do all these acids have in common:
Strong Acids
The Formula
Sulphuric acid
Hydrochloric acid
Hydrobromic acid
Hydroiodic acid
Nitric acid
Perchloric acid
H2SO4
HCl
HBr HI
HNO3
HClO4
Weak Acid The Formula
Acetic acid (vinegar) HC2H3O2
Carbonic acid HCO3

3. Acid:
A substance that ionises (breaks down into ions) and releases H+ ions in an aqueous solution
“aqueous” means: water

4. Characteristics of Acids:
Acids have a sour taste
Acids react with metals (to produce hydrogen gas)
Acids have a pH of 1-6
Acids turn universal indicator yellow, orange or red
Acids turn litmus red
Many are corrosive or poisonous

5. You need to know three acids
Sulfuric acid
H2SO4
hydrochloric acid
HCl
Nitric acid
HNO3

6. All are Strong Acids
Ionise (break down into ions) completely to give off many H+ ions

8. Weak Acids
(only partially breaks down (ionise), gives less H+)

9. What do these bases have in common:
Strong Bases
The Formulae
Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Rubidium hydroxide
Caesium hydroxide
Barium hydroxide
Calcium hydroxide
Strontium hydroxide
LiOH
NaOH
KOH
RbOH
CsOH
Ba(OH)2
Ca(OH)2
Sr(OH)2

10. Base:
A substance that ionises and releases OH- ions in an aqueous solution
Alkali:
A base that dissolves in water

11. OH- Characteristics of Bases: Bases usually taste bitter
Bases feel slippery
Bases have a pH of 8 – 14
Bases turn universal indicator blue or purple
Bases turn litmus blue
OH-

12. BUT AREN’T METAL OXIDES BASES?
Yes!!!!!!
Metal oxide + water  metal hydroxide
Metal oxides release hydroxide ions in solution

13. Some bases (VERY FEW)
don’t have or produce OH-
Examples include:
ammonia NH3
Carbonates (CO3 and HCO3)
***Any chemical which neutralizes an acid can be considered a base

14. Indicators
An indicator is a compound that will change color in the presence of an acid or base
Red Litmus-Turns blue in base
Blue Litmus-Turns red in acid
Universal indicator (pH paper) Used for the full pH range
Phenolphthalein-Turns pink in base

15. pH
pH stands for “potential of Hydrogen” and is a measure of how many H+ ions there are in solution.
The MORE H+ there are, the LOWER the pH will be.

16. Shows the range of H+ concentrations
pH Scale
Shows the range of H+ concentrations
High H+ concentration
Low H+ concentration

17. Reactions between acids and bases
When an acid and a base react with each other , the characteristic properties of both are destroyed. This is called neutralisation.
This happens because equal amounts of the two substances cancel each others properties and produce two neutral substances (water and a salt).

18. Reactions between acids and bases
General formula for acid base reaction: → + +
Base
Water
Salt
Acid
“Salt” means any ionic compound formed from an acid/base reaction
NOT JUST
NaCl !!

19. Neutralisation
HCl + NaOH → H2O + NaCl
acid base water salt

20. Neutralisation H Cl K OH Another Example HCl + KOH → H2O + KCl
acid base water salt

21. Complete and incomplete neutralisation
Any time an acid and base react neutralisation will occur. However, whether the solutions are fully neutralised depends on several factors:
The pH of both reactants
The concentration of both reactants
The quantity of both reactants
If any of these factors occur then neutralisation will be incomplete. This means in the solution there will be a metal salt, water and an acid or base.

22. Name the following compounds
CaO
NaOH
Na2S
PbCO3
CuHCO3
Ag2O
PbCl2
CuSO4

23. General equations
These are all extensions of the acid + base equations
Acid + metal oxide metal salt + water
Acid + metal hydroxide Metal salt + water
Acid + Metal carbonate metal salt+ water + carbon dioxide
Acid + metal hydrogen carbonate metal salt + water+ carbon dioxide

24. WHAT SALT IS FORMED DEPENDS ON WHAT ACID IS USED
Hydrochloric acid makes a chloride salt
Sulfuric acid makes a sulfate salt
Nitric acid makes a nitrate salt

25. Predict what acid these salts were made from
NaNO3
CaSO4
PbCl2
CuCl2
Fe2(SO4)3
Fe(NO3)2

26. Complete the following as word equations only
Hydrochloric acid + Calcium hydroxide
Sulphuric acid + Lead oxide
Nitric acid + sodium bi-carbonate
Silver oxide + sulphuric acid
Copper carbonate + nitric acid

27. 2. Balancing word equations
Calcium oxide + Hydrochloric acid Calcium chloride + water
Nitric acid + copper carbonate copper nitrate + water + carbon dioxide
Hydrochloric acid + lead hydroxide lead chloride + water
Copper oxide + sulphuric acid copper sulphate + water
Sodium hydrogen carbonate + nitric acid sodium nitrate + water + carbon dioxide

28. NCEA 2009
A student carried out an experiment to neutralise sulfuric acid by adding sodium hydroxide to it.
Discuss how the student could have determined when the sulfuric acid had been neutralised and what effect adding the sodium hydroxide has on the pH of the solution.
In your answer include:
• an explanation of neutralisation in terms of an acid-base reaction
• the name of the indicator used
• observations that the student would make as the sodium hydroxide is added to the acid
• a word and balanced chemical equation for the reaction.

30. NCEA 2006 The pH values of three substances are given below:
Hydrochloric acid pH = 1
Potassium carbonate solution pH = 9
Sodium hydroxide solution pH = 14
(a) When Universal Indicator solution is added to each of these substances, what colour would result?
(i) Hydrochloric acid __________________
(ii) Potassium carbonate solution __________________
(iii) Sodium hydroxide solution __________________
Potassium carbonate solution is added slowly to the hydrochloric acid (without indicator) in a beaker until no further change is seen.
(b) (i) Describe what you would see happening when potassium carbonate is added to the acid.
(ii) Write a balanced chemical equation for the reaction between potassium carbonate and hydrochloric acid.

34. NCEA QUESTION
HCl is added to a solution of sodium hydroxide. The reaction takes place but complete neutralisation did not occur. Discuss three things that could have lead to this.

35. TRY THESE – IN WORDS AND THEN BALANCED CHEMICAL EQUATIONS
Hydrochloric acid + potassium hydroxide
Sulfuric acid + calcium oxide
Sulfuric acid + sodium hydroxide