1. Acids Bases & Salts (Acids)
an e-learning series by ycs

2. Learning Objectives By the end of the lesson, pupils would be able to
Define the meaning of acids
Name common acids
Explain the importance of water as solvent
Describe the physical properties of acids
Describe the chemical reaction of acids
Explain the basicity of acids

3. Types of Acids Mineral acids Organic acids hydrochloric acid, HCl
nitric acid, HNO3
sulphuric acid, H2SO4
Organic acids
ethanoic acid (vinegar), CH3COOH

4. Definition
A substance when dissolved in water produces hydrogen ions as the only positive ions
HCl (aq)  H+ (aq) + Cl- (aq)
click icon
H+ ion

5. Releasing the H+ ions
Water is needed for the release of H+ ions and not organic solvent.
e.g. If the gas hydrogen chloride, HCl(g), is dissolved in methylbenzene, no H+ ions would be produced.

6. What does the H+ do?
The hydrogen ion is responsible for the properties and chemical reactions of acids.
What are some properties and chemical reactions of acids?

7. Properties of Acids Sour taste Turns blue litmus red
Changes the colour of indicators like universal indicator, methyl orange..etc

8. Indicators & pH Scale
Click on the pH Scale below to learn more about indicators and the pH.
The pH Scale

9. Chemical Reactions
Acids react with metals to form salt and hydrogen gas.
Mg(s) + 2HCl(aq)  MgCl2(aq) + H2(g)
Fe(s) + 2HNO3(aq)  Fe(NO3)2(aq) + H2(g)
Ca(s) + H2SO4(aq)  CaSO4(aq) + H2(g)

10. Chemical Reactions
Acids react with carbonates to form salt, water and carbon dioxide gas.
CaCO3(s) + 2HCl(aq) 
CaCl2(aq) + H2O(l) + CO2(g)
Na2CO3(s) + H2SO4(aq) 
Na2SO4(aq) + H2O(l) + CO2(g)

11. Chemical Reactions Acids react with bases to form salt and water.
NaOH(aq) + HNO3(aq)  NaNO3(aq) + H2O(l)
CuO(s) + 2HCl(aq)  CuCl2(aq) + H2O(l)
This reaction is known as neutralisation and is represented by the ionic equation,
H+ (aq) + OH- (aq)  H2O (l)

12. Basicity of Acids
If an acid contains one replaceable hydrogen, it is a monobasic acid
What can you say about dibasic and tribasic?
Determine the basicity of these acids,
HCl
H2SO4
H3PO4

13. Nutshell Activity
Write the chemical equations for the following reaction
calcium + dilute hydrochloric acid
Iron(II) carbonate + dilute nitric acid
magnesium oxide + dilute sulphuric acid

14. Nutshell Activity
Hydrogen chloride was bubbled into an organic solvent, methylbenzene. The resulting solution has no effect on litmus paper. Explain this observation.

15. Nutshell Activity
Acids contain replaceable hydrogen. For each hydrogen replaced by a positive ion, a salt is produced. How many types of salts can be produced from a dibasic acid?
Give an example of a monobasic, dibasic and tribasic acid.

16. Extension
To learn more about the topic on acids you can follow this link here to Chinese High School Chemistry VLE’s webpage.