making salts
DESCRIPTION
Making Salts. Acid + excess insoluble solid. Acid + alkali titration. Acid + reactive metal. Soluble salt. Acid + base. Acid + carbonate. Insoluble salt. Direct combination. Precipitation. Reactions of acids. Neutralisation of: hydrochloric acid gives a chloride - PowerPoint PPT PresentationTRANSCRIPT
Making Salts
Soluble salt
Acid + reactive metal
Acid + base
Acid + carbonate
Acid + excess insoluble solid
Acid + alkali titration
Insoluble saltPrecipitation
Direct combination
Neutralisation of:
hydrochloric acid gives a chloride
sulphuric acid gives a sulphate
nitric acid gives a nitrate
Acid + metal salt + hydrogen
Acid + base* salt + water
Acid + carbonate salt + water + carbon dioxide
*Base: A metal oxide or metal hydroxide.
An alkali is a water-soluble base.
Reactions of acids
Salts
A salt is an ionic compound which is neither an acid (containing H+) or a base (containing O2- or OH-). A salt is formed whenever an acid is neutralised.
Ionic compounds
Acids, containing H+
Bases, containing OH- or O2-
Salts
Uses of Salts
• Plant fertilisers (NPK)– (NH4)2SO4, NH4NO3, KH2PO4, …….
• Food flavour and preservation– NaCl, KCl, KNO3…….
• In toothpaste– NaF
• Photographic film– AgCl, AgBr
Salts are important also in:
• Proteins and enzymes– The molecules that carry out the chemical
reactions of life
• DNA and RNA– the molecules of inheritance
• Transmission of electrical impulses along nerves
Neutralisation of:
hydrochloric acid gives a chloride (containing Cl-)
sulphuric acid gives a sulphate (containing SO42-)
nitric acid gives a nitrate (containing NO3-)
Acid + metal salt + hydrogen
Acid + base salt + water
Acid + carbonate salt + water + carbon dioxide
Acid Neutralisation reactions
Acid + alkali salt + water
HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l)
Titration of acid against alkali for soluble salts of group 1 metals and ammonium
5 cm3 sodium hydroxide solution was measured using a pipette and transferred to the conical flask. 2 drops of methyl orange indicator were added. Hydrochloric acid was poured into the burette and the starting reading was recorded. The acid was added to the sodium hydroxide, drop by drop, until the indicator turned from yellow to orange (or red). Charcoal was added to the mixture to absorb the indicator and was removed by filtration. Water was evaporated from the filtrate, leaving sodium chloride crystals.
Methods of salt making (1)
Methods of salt making (2)
• Acid + excess insoluble solid– For all other soluble salts
– Solid is either a moderately reactive metal, a base or a carbonate
– Excess solid to react with all the acid• Removed by filtration
Methods of salt making (3)
• Precipitation reactions– To make insoluble salts– 2 solutions each containing one of the ions in
the salt are mixed.– Salt is precipitated– Salt is filtered, residue is washed on filter paper
and dried.
Methods of salt making (4)
• Direct combination of the elements
sodium (l) + chlorine (g) sodium chloride (s)
2 Na (l) + Cl2 (g) 2 NaCl (s)
aluminium (s) + bromine (l) aluminium bromide (s)
2 Al (s) + 3 Br2 (l) 2 Al Br3 (s)
barium hydroxide (aq) + nitric acid (aq)
Ba(OH)2 (aq) + HNO3 (aq)
barium nitrate (aq) + water (l)
Ba(NO3)2 (aq) + H2O (l)
2
2
(a)
Methods of salt making (1)
ammonium carbonate (aq) + sulphuric acid (aq)
(NH4)2CO3 (aq) + H2SO4 (aq)
ammonium sulphate (aq) + water (l) + carbon dioxide (g)
(NH4)2SO4 (aq) + H2O (l) + CO2 (g)
(b)
Methods of salt making (1)
ammonium hydroxide (aq) + nitric acid (aq)
NH4OH (aq) + HNO3 (aq)
ammonium nitrate (aq) + water (l)
NH4NO3 (aq) + H2O (l)
(c)
Methods of salt making (1)
potassium hydroxide (aq) + nitric acid (aq)
KOH (aq) + HNO3 (aq)
potassium nitrate (aq) + water (l)
KNO3 (aq) + H2O (l)
(e)
Methods of salt making (1)
Methods of salt making (2)
Acid + insoluble base salt + water
H2SO4 (aq) + CuO (s) CuSO4 (aq) + H2O (l)
calcium (s) + nitric acid (aq)
Ca (s) + HNO3 (aq)
calcium chloride(aq) + hydrogen (g)
Ca(NO3)2 (aq) + H2 (g)
2
(g)
Methods of salt making (2)
iron (s) + sulphuric acid (aq)
Fe (s) + H2SO4 (aq)
iron (II) sulphate (aq) + hydrogen (g)
FeSO4 (aq) + H2 (g)
(f)
Methods of salt making (2)
calcium carbonate (s) + nitric acid (aq)
CaCO3 (s) + HNO3 (aq)
calcium nitrate (aq) + water (l) + carbon dioxide (g)
Ca(NO3)2 (aq) + H2O (l) + CO2 (g)
2
(d)
Methods of salt making (2)
Acid + metal salt + hydrogen
Magnesium + hydrochloric acid magnesium chloride + hydrogen
Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g)
Mg (s) + 2 H+ 2 Cl- (aq) Mg2+ 2 Cl- (aq) + H2 (g)
copper + hydrochloric acid no reaction
Cu (s) + 2 HCl (aq)
Cu (s) + 2 H+ 2 Cl- (aq)
2 e-
Metal Reactivity Series
Potassium
Sodium
Lithium
Calcium
Magnesium
Zinc
Iron
Lead
Hydrogen
Copper
Silver
Gold
Platinum
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Acid + base salt + water
Sulphuric acid + copper oxide copper sulphate + water
H2SO4 (aq) + CuO (s) CuSO4 (aq) + H2O (l)
2 H+ SO42- (aq) + Cu2+ O2- (s) Cu2+ SO4
2- (aq) + H2O (l)
Sulphuric acid + copper hydroxide copper sulphate + water
H2SO4 (aq) + Cu(OH)2 (s) CuSO4 (aq) + 2 H2O (l)
2 H+ SO42- (aq) + Cu2+ 2 OH- (s) Cu2+ SO4
2- (aq) + 2 H2O (l)
Carbonic acid
• H2CO3 (aq)
• 2 H+ CO32- (aq)
• Present in fizzy drinks:H2CO3 (aq) CO2 (g) + H2O (l)
Acid +carbonate salt + water + carbon dioxide
Sulphuric acid + nickel carbonate nickel sulphate + water + carbon dioxide
H2SO4 (aq) + NiCO3 (s) NiSO4 (aq) + H2O (l) + CO2 (g)
2 H+ SO4
2- (aq) + Ni2+ CO32- (s) Ni2+ SO4
2- (aq) + H2CO3 (aq)+ H2O (l) + CO2 (g)