ACIDS, BASES
AND SALTS
A guide for A level students
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KNOCKHARDY PUBLISHING
ACIDS, BASES AND SALTS
INTRODUCTION
This Powerpoint show is one of several produced to help students understand
selected topics at AS and A2 level Chemistry. It is based on the requirements of the
AQA and OCR specifications but is suitable for other examination boards.
Individual students may use the material at home for revision purposes or it may be
used for classroom teaching if an interactive white board is available.
Accompanying notes on this, and the full range of AS and A2 topics, are available
from the KNOCKHARDY SCIENCE WEBSITE at...
www.knockhardy.org.uk/sci.htm
Navigation is achieved by...
either
clicking on the grey arrows at the foot of each page
or
using the left and right arrow keys on the keyboard
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ACIDS AND BASES
BRØNSTED-LOWRY THEORY
ACID
proton donor
HCl ——> H+(aq) + Cl¯(aq)
BASE
proton acceptor
NH3(aq) + H+(aq)
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——>
NH4+(aq)
ACIDS
ACIDS
proton donors
release H+ ions (protons) in aqueous solution
STRONG ACIDS
Hydrochloric
HCl —> H+(aq) + Cl¯(aq)
1 replaceable H
MONOPROTIC
Nitric
HNO3 —> H+(aq) + NO3¯(aq)
1 replaceable H
MONOPROTIC
Sulphuric
H2SO4 —> 2H+(aq) + SO42-(aq)
2 replaceable H’s
DIPROTIC
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ACIDS
ACIDS
proton donors
release H+ ions (protons) in aqueous solution
STRONG ACIDS
Hydrochloric
HCl —> H+(aq) + Cl¯(aq)
1 replaceable H
MONOPROTIC
Nitric
HNO3 —> H+(aq) + NO3¯(aq)
1 replaceable H
MONOPROTIC
Sulphuric
H2SO4 —> 2H+(aq) + SO42-(aq)
2 replaceable H’s
DIPROTIC
WEAK ACIDS
Ethanoic
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CH3COOH(aq)
CH3COO¯(aq) +
H+(aq)
MONOPROTIC
BASES AND ALKALIS
BASES
e.g.
proton acceptors
carbonates
hydrogencarbonates
metal oxides
metal hydroxides
ammonia
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react with acids by accepting H+ ions to form salts
K2CO3
NaHCO3
MgO
NaOH
NH3
MgCO3
CuCO3
ZnO
KOH
CuO
Ca(OH)2
BASES AND ALKALIS
BASES
e.g.
ALKALIS
e..g.
proton acceptors
react with acids by accepting H+ ions to form salts
carbonates
hydrogencarbonates
metal oxides
metal hydroxides
ammonia
K2CO3
NaHCO3
MgO
NaOH
NH3
MgCO3
CuCO3
ZnO
KOH
CuO
Ca(OH)2
SOLUBLE BASES which release OH¯ (hydroxide ions) in aqueous solution
Soluble metal oxides
sodium oxide
Na2O + H2O(l) ——> 2Na+(aq) + 2OH¯(aq)
Soluble metal hydroxides
sodium hydroxide
potassium hydroxide
NaOH
KOH
Aqueous ammonia
or
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——>
——>
NH3(aq) + H2O(l)
NH3(aq) + H+(aq)
Na+(aq) + OH¯(aq)
K+(aq) + OH¯(aq)
NH4+ (aq) + OH¯(aq)
NH4+(aq)
SALTS
SALTS
Formed from the reaction between acids and bases
hydrochloric acid makes CHLORIDES
nitric acid
makes NITRATES
sulphuric acid
makes SULPHATES / HYDROGENSULPHATES
SALT
FORMATION
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A salt is produced when the H+ ion of an acid is replaced by...
a metal ion
or
the ammonium ion NH4+
SALTS
SALTS
Formed from the reaction between acids and bases
hydrochloric acid makes CHLORIDES
nitric acid
makes NITRATES
sulphuric acid
makes SULPHATES / HYDROGENSULPHATES
SALT
FORMATION
A salt is produced when the H+ ion of an acid is replaced by...
a metal ion
or
the ammonium ion NH4+
SUMMARY
Acids react with...
metals
oxides of metals
hydroxides of metals
carbonates
hydrogencarbonates
ammonia
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to give
a salt + hydrogen
a salt + water
a salt + water
a salt + water + carbon dioxide
a salt + water + carbon dioxide
an ammonium salt
WATER OF CRYSTALLISATION
Water of
crystallisation
• loosely bonded water molecules attached to salts
CuSO4.5H2O
FeSO4.7H2O
Na2CO3.10H2O
• the water can be driven off by heating
e.g.
CuSO4.5H2O(s)
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———>
CuSO4(s)
+
5H2O(l)
WATER OF CRYSTALLISATION
Water of
crystallisation
• loosely bonded water molecules attached to salts
CuSO4.5H2O
FeSO4.7H2O
Na2CO3.10H2O
• the water can be driven off by heating
e.g.
CuSO4.5H2O(s)
HYDRATED copper(II) sulphate
BLUE CRYSTALS
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———>
CuSO4(s) +
5H2O(l)
ANHYDROUS copper(II) sulphate
WHITE POWDER
REACTIONS OF HYDROCHLORIC ACID
Is a typical acid in dilute aqueous solution
Hydrogen chloride is a colourless
covalent gas; it is a poor conductor
of electricity because there are no
free electrons or ions present. It
has no action on dry litmus paper
because there are no aqueous
hydrogen ions present.
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HCl
——> H+ (aq)
+ Cl¯(aq)
REACTIONS OF HYDROCHLORIC ACID
Is a typical acid in dilute aqueous solution
Hydrogen chloride is a colourless
covalent gas; it is a poor conductor
of electricity because there are no
free electrons or ions present. It
has no action on dry litmus paper
because there are no aqueous
hydrogen ions present.
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HCl
——> H+ (aq)
+ Cl¯(aq)
If the gas is passed into water, the hydrogen
chloride molecules dissociate into ions. The
solution now conducts electricity showing
ions are present. For each hydrogen
chloride molecule that dissociates one
hydrogen ion and one chloride ion are
produced. The solution turns litmus paper
red because of the H+(aq) ions.
REACTIONS OF HYDROCHLORIC ACID
Is a typical acid in dilute aqueous solution
Hydrogen chloride is a colourless
covalent gas; it is a poor conductor
of electricity because there are no
free electrons or ions present. It
has no action on dry litmus paper
because there are no aqueous
hydrogen ions present.
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HCl
——> H+ (aq)
+ Cl¯(aq)
If the gas is passed into water, the hydrogen
chloride molecules dissociate into ions. The
solution now conducts electricity showing
ions are present. For each hydrogen
chloride molecule that dissociates one
hydrogen ion and one chloride ion are
produced. The solution turns litmus paper
red because of the H+(aq) ions.
REACTIONS OF HYDROCHLORIC ACID
Is a typical acid in dilute aqueous solution
HYDROGEN CHLORIDE
colourless gas
covalent molecule
HCl(g)
poor
no reaction
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HCl
——> H+ (aq)
+ Cl¯(aq)
HYDROCHLORIC ACID
Appearance
Bonding
Formula
Conductivity
Dry blue litmus
colourless soln.
aqueous ions
HCl(aq)
good
goes red
REACTIONS OF HYDROCHLORIC ACID
SUMMARY
Is a typical acid in dilute aqueous solution
Hydrogen chloride is a colourless
covalent gas; it is a poor conductor
of electricity because there are no
free electrons or ions present. It
has no action on dry litmus paper
because there are no aqueous
hydrogen ions present.
hydrogen chloride
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hydrochloric
acid
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Appearance
colourless gas
colourless soln.
HCl
——> H+ (aq)
+ Cl¯(aq)
If the gas is passed into water, the hydrogen
chloride molecules dissociate into ions. The
solution now conducts electricity showing
ions are present. For each hydrogen
chloride molecule that dissociates one
hydrogen ion and one chloride ion are
produced. The solution turns litmus paper
red because of the H+(aq) ions.
Bonding and formula
covalent molecule HCl(g)
aqueous ions HCl(aq)
Conductivity
poor
good
Dry litmus
no reaction
goes red
REACTIONS OF HYDROCHLORIC ACID
Metals
magnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen
Mg(s)
1.
+
2HCl(aq)
——>
MgCl2(aq)
WRITE OUT THE BALANCED EQUATION FOR THE REACTION
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+
H2(g)
REACTIONS OF HYDROCHLORIC ACID
Metals
magnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen
Mg(s)
Mg(s)
1.
2.
+
+
2HCl(aq)
2H+(aq) + 2Cl¯(aq)
——>
——>
MgCl2(aq)
+
H2(g)
Mg2+(aq) + 2Cl¯(aq) + H2(g)
WRITE OUT THE BALANCED EQUATION FOR THE REACTION
DILUTE ACIDS AND SALTS CONTAIN IONS; WATER, HYDROGEN & CARBON DIOXIDE DON’T
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REACTIONS OF HYDROCHLORIC ACID
Metals
magnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen
Mg(s)
Mg(s)
+
+
2H+(aq) + 2Cl¯(aq)
cancel ions
1.
2.
3.
——>
2HCl(aq)
Mg(s)
——>
+ 2H+(aq)
MgCl2(aq)
+
H2(g)
Mg2+(aq) + 2Cl¯(aq) + H2(g)
——>
Mg2+(aq) +
H2(g)
WRITE OUT THE BALANCED EQUATION FOR THE REACTION
DILUTE ACIDS AND SALTS CONTAIN IONS; WATER, HYDROGEN & CARBON DIOXIDE DON’T
CANCEL OUT THE IONS WHICH APPEAR ON BOTH SIDES OF THE EQUATION
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REACTIONS OF HYDROCHLORIC ACID
Metals
magnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen
Mg(s)
Mg(s)
+
+
2H+(aq) + 2Cl¯(aq)
cancel ions
Basic
Oxides
Mg(s)
copper(II) oxide
CuO(s)
Cu2+O2-(s)
——>
2HCl(aq)
+
+
+ 2H+(aq)
2HCl(aq)
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——>
+
——>
——>
Mg2+(aq) +
CuCl2(aq)
——>
H2(g)
copper(II) chloride + water
——> Cu 2+ (aq) + 2Cl¯(aq)
O2- + 2H+(aq)
H2(g)
Mg2+(aq) + 2Cl¯(aq) + H2(g)
dil. hydrochloric acid
+ 2H+(aq) + 2Cl¯(aq)
cancel ions
——>
MgCl2(aq)
H2O(l)
+
H2O(l)
+
H2O(l)
REACTIONS OF HYDROCHLORIC ACID
Alkalis
sodium hydroxide + dil. hydrochloric acid
NaOH(aq)
Na+(aq) + OH¯(aq)
cancel ions
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+
HCl(aq)
+ H+(aq) + Cl¯(aq)
——>
——> sodium chloride + water
NaCl(aq)
+
——> Na+ (aq) + Cl¯(aq)
H+(aq) + OH¯(aq)
——>
H2O(l)
H2O(l)
+
H2O(l)
REACTIONS OF HYDROCHLORIC ACID
Alkalis
——> sodium chloride + water
sodium hydroxide + dil. hydrochloric acid
NaOH(aq)
Na+(aq) + OH¯(aq)
cancel ions
Carbonates
+
HCl(aq)
+ H+(aq) + Cl¯(aq)
——>
NaCl(aq)
+
H2O(l)
——> Na+ (aq) + Cl¯(aq)
H+(aq) + OH¯(aq)
——>
+
H2O(l)
H2O(l)
calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water
CaCO3(s)
+
2HCl(aq)
Ca2+CO32-(s) + 2H+(aq) + 2Cl¯(aq)
cancel ions
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——>
CaCl2(aq)
+
CO2(g) + H2O(l)
——> Ca2+(aq) + 2Cl¯(aq) + CO2(g) + H2O(l)
CO32- + 2H+(aq)
——>
CO2(g) + H2O(l)
REACTIONS OF HYDROCHLORIC ACID
Alkalis
——> sodium chloride + water
sodium hydroxide + dil. hydrochloric acid
NaOH(aq)
Na+(aq) + OH¯(aq)
cancel ions
Carbonates
+
HCl(aq)
+ H+(aq) + Cl¯(aq)
——>
NaCl(aq)
+
H2O(l)
——> Na+ (aq) + Cl¯(aq)
H+(aq) + OH¯(aq)
——>
+
H2O(l)
H2O(l)
calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water
CaCO3(s)
+
2HCl(aq)
Ca2+CO32-(s) + 2H+(aq) + 2Cl¯(aq)
cancel ions
Hydrogen carbonates
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——>
CaCl2(aq)
+
CO2(g) + H2O(l)
——> Ca2+(aq) + 2Cl¯(aq) + CO2(g) + H2O(l)
CO32- + 2H+(aq)
——>
H+(aq) + HCO3¯ ——>
CO2(g) + H2O(l)
CO2(g)
+
H2O(l)
REACTIONS OF HYDROCHLORIC ACID
SUMMARY
METALS
react to give
a salt + hydrogen
METAL OXIDES
react to give
a salt + water
METAL HYDROXIDES
react to give
a salt + water
CARBONATES
react to give
a salt + water + carbon dioxide
HYDROGENCARBONATES
react to give
a salt + water + carbon dioxide
AMMONIA
reacts to give
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an ammonium salt
ACIDS, BASES
AND SALTS
THE END
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