Acids Bases & Salts (Acids)
an e-learning series by ycs
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
Types of Acids
• Mineral acids
– hydrochloric acid,
HCl
– nitric acid, HNO3
– sulphuric acid,
H2SO4
• Organic acids
– ethanoic acid
(vinegar), CH3COOH
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
+
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.
+
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?
Properties of Acids
• Sour taste
• Turns blue litmus red
• Changes the colour of indicators like
universal indicator, methyl orange..etc
Indicators & pH Scale
• Click on the pH Scale below to learn
more about indicators and the pH.
The pH Scale
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)
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)
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)
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
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
Nutshell Activity
• Hydrogen chloride was bubbled into an
organic solvent, methylbenzene. The
resulting solution has no effect on litmus
paper. Explain this observation.
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.
Extension
• To learn more about the topic on acids
you can follow this link here to Chinese
High School Chemistry VLE’s webpage.