PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
Acids, Bases and Salts
PAL (IGCSE) Chemistry
Revision Book - Section 8
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PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
Syllabus Content_______________________________
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PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
Syllabus Details________________________________
8. Acids, bases and salts
8.1 The characteristic properties of acids and bases
Core
• Describe the characteristic properties of acids as reactions with metals, bases, carbonates
and effect on litmus
Reactions of ACIDS with METALS
Acid +
Metal
Salt
Hydrochloric Acid + Magnesium
2HCl + Mg
Sulphuric Acid
+
Hydrogen
Magnesium chloride + Hydrogen
MgCl2 + H2
Zinc
H2SO4 + Zn
+
Zinc sulphate +
ZnSO4
Hydrogen
+ H2
Reactions of ACIDS with BASES
Acid +
Base
Salt
Hydrochloric Acid + Sodium hydroxide
HCl + NaOH
Sulphuric Acid
+
+
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Sodium chloride + Water
Calcium hydroxide
Calcium sulphate +
CaSO4
Potassium hydroxide
HNO3 + KOH
Water
NaCl + H2O
H2SO4 + Ca(OH)2
Nitric Acid
+
KNO3
Water
+ 2H2O
Potassium nitrate +
Water
+ H2O
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PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
Reactions of ACIDS with CARBONATES
Acid + Carbonate
Salt + Water + Carbon Dioxide
Hydrochloric Acid + Sodium carbonate
2HCl + Na2CO3
Sodium chloride + Water + Carbon dioxide
2NaCl + H2O + CO2
Acid + Hydrogencarbonate
Salt + Water + Carbon Dioxide
Hydrochloric Acid + Sodium hydrogencarbonate
HCl + NaHCO3
Sodium chloride + Water + Carbon dioxide
NaCl + H2O
+ CO2
ACIDS TURN BLUE LITMUS RED
• Describe the characteristic properties of bases as reactions with acids and with ammonium
salts and effect on litmus
Neutralization Reactions
Acid +
Base
Salt
Hydrochloric Acid + Sodium hydroxide
HCl + NaOH
+
Sodium chloride + Water
NaCl + H2O
H+(aq) + OH- (aq)
Hydrogen ion
+
Water
Hydroxide ion
H2O(l)
Water
BASES TURN RED LITMUS BLUE
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PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
Reactions of Bases with Ammonium salts
Base + Ammonium salt
Salt
Sodium hydroxide + Ammonium chloride
NaOH + NH4Cl
+ Water + Ammonia
Sodium chloride + water + ammonia
NaCl + H2O + NH3
• Describe neutrality and relative acidity and alkalinity in terms of pH (whole numbers only)
measured using Universal Indicator paper
pH Scale
1 2
3 4 5 6 7
8 9 1 0 11 12 13 14
ACIDS
ALKALIS
NEUTRAL
• Describe and explain the importance of controlling acidity in soil
Acidity in soil
 Plants prefer a certain degree of acidity or alkalinity
o E.g. Potatoes pH 4.5 – 6.0
 Too acid or basic soil will lead to plants dying
 The acidity can be controlled by using…
o Lime to reduce acidity
o Peat to increase acidity
Supplement
• Define acids and bases in terms of proton transfer, limited to aqueous solutions
ACIDS: A molecule or ion that is able to donate a proton (H+) to a base
BASES: A molecule or ion that is able to accept a proton (H+)
• Describe the meaning of weak and strong acids and bases
Strong acids: Completely ionized in solution in water
Weak acids: Partially dissociated in solution in water
Strong bases: Completely ionized in solution in water
Weak bases: Partially dissociated in solution in water
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PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
8.2 Types of oxides
Core
• Classify oxides as either acidic or basic, related to metallic and non-metallic character
Supplement
• Further classify other oxides as neutral or Amphoteric
Non-metal Oxides
Acidic
CO2, SO2
Metal Oxides
Neutral
H2O, CO, NO
Amphoteric
ZnO, Al2O3
Basic
CaO, MgO, CuO
8.3 Preparation of salts
Core
• Describe the preparation, separation and purification of salts as examples of some of the
techniques specified in section 2.2(b) and the reactions specified in section 8.1
Supplement
• Describe the preparation of insoluble salts by precipitation
Precipitation: The sudden formation of solid in a solution due to…
 the mixing of two solutions
 or the bubbling of gas through the solution
BaCl2(aq) + Na2SO4(aq)
2NaCl(aq) + BaSO4(s)
Precipitate
Salt
Soluble salt in
water
Insoluble salt in
water
Separation technique
Evaporation
Purification
Re-dissolve and evaporate
Filtration
Re-dissolve and evaporate
Steps to preparation of a salt
 Place acid in a burette
 Measure known volume of base in a beaker
 Add suitable indicator to base (blue litmus)
 Add acid drop-wise until colour change
 Record volume of acid added
 Repeat process without the indicator
• Suggest a method of making a given salt from suitable starting material, given appropriate
information
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PAL (IGCSE) – CHEMISTRY
Section 8 Acids, Bases and Salts
8.4 Identification of ions and gases
Core
• Describe the following tests to identify:
aqueous cations: aluminium, ammonium, calcium, copper(II), iron(II), iron(III) and zinc (using
aqueous sodium hydroxide and aqueous ammonia as appropriate) (Formulae of complex ions
are not required.)
anions:
carbonate (by reaction with dilute acid and then limewater), chloride (by reaction under acidic
conditions with aqueous silver nitrate), iodide (by reaction under acidic conditions with
aqueous silver nitrate), nitrate (by reduction with aluminium), sulfate
(by reaction under acidic conditions with aqueous barium ions)
gases:
ammonia (using damp red litmus paper), carbon dioxide (using limewater), chlorine (using
damp litmus paper), hydrogen (using lighted splint), oxygen (using a
glowing splint).
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