Preparation of Salts
Salts


Salts are compounds of nitrates, NO3-1, Sulfates,SO4-2, Chlorides,
Cl-, carbonates, CO3-2, etc.
Salts are neutral in pH.

Solubility of Salts

Soluble
All Nitrates
All Sulfates
All Chlorides
Group 1 salts, Ammonium
salts
K2CO3, Na2CO3, NH4CO3
K2O, Na2O
Metal oxides are not salts,
but bases or alkalis (if
soluble)
Insoluble
BaSO4, CaSO4, PbSO4
AgCl, PbCl
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Titration Method (Soluble Base + Acid)
To prepare any salt that is from Group 1. (Eg. Preparing Sodium
Sulfate).
All Carbonates
All Oxides
Remember via: “Baked
Chicken Pasta At
Pastamania”
(So to prepare sodium sulfate we need sulfuric acid + Sodium
Hydroxide.)
H2SO4 + 2NaOH
Na2SO4 + 2H2O
Facts of table:
o
o
o
o
Soluble Salts are prepared by:
1- Titration method (Soluble Base + Acid), to prepare any salt
from group 1.
2- Reacting metal + acid or insoluble metal oxide + acid or metal
carbonate + acid (to prepare soluble salts other than group 1)
Insoluble salts are prepared by Precipitation method (soluble salt
+ soluble salt is used).
All Nitrates are soluble
All Carbonates that are from group 1 in the periodic table are
soluble; the rest are insoluble. Eg. Potassium Carbonate is
soluble, Barium Carbonate is insoluble
All sulfates are soluble except Barium Sulfate, Calcium, Lead.
Eg. Zinc sulfate is soluble while Calcium sulfate is insoluble
All Chlorides are soluble except Silver Chloride, Lead
Chloride.. Eg. Calcium Chloride is soluble, Lead Chloride is
insoluble
1) Add 25cm3 of acid to a conical flask
2) Add a few drops of indicator. (eg. Phenol‐ Phthalein)
3) Add Sodium Hydroxide using a burette until indicator changes
colour.
4) Repeat experiment with 25cm3 of Sulfuric Acid but NO indicator!
5) Add same volume of Sodium Hydroxide.
6) Sodium Sulfate is obtained by evaporating & crystalising the salt.
Reacting metal + acid or insoluble metal oxide + acid or metal
carbonate + acid (to prepare soluble salts other than group 1)
Only metals like zinc and magnesium, which moderately react with
dilute acids, are used.
 So is Magnesium Sulfate soluble? YES.
 Is Sodium Carbonate soluble? YES.
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Chemistry Dept/Grade9/First Term/2014
Imaduddin School
Precipitation Method (Soluble salt+ Soluble salt)
E.g. Reacting Zn with H2SO4 to prepare ZnSO4
To prepare any Insoluble salt. (Eg. Preparing Silver Chloride)
AgNO3 (aq) + NaCl (aq) → NaNO3 (aq) + AgCl (s)
Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2O(l)
1) Add Silver Nitrate with Sodium Chloride.
2) Filter out the precipitate, AgCl.
3) Wash the residue with distilled water.
4) Leave the residue to dry.
To use precipitation, just make sure the salt you want to make is
insoluble. The method requires you to use “Soluble salt + Soluble salt”
so using the table, just find 2 salts that are soluble and contain part of
the name.
For example, I want to make an insoluble salt
called “Calcium Sulfate”.
Zn is added to H2SO4 until in excess to ensure no more H2SO4 is
present. Then the mixture is filtered off to separate Zn from ZnSO 4.
The filtrate (ZnSO4) is then placed in evaporating dish to evaporate
most of water then it’s cooled after ZnSO4 crystals are formed. The
crystals then filtered and squeezed between filter papers to dry.
By Reacting Insoluble Base with Acid
E.g. Reacting MgO with Acids
MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l)
The same method as reaction of acid with metal is used, so refer to
diagram and above explanation, substituting reactants and products.
1st, I need to find “Calcium‐~ ” that is soluble. And I also know that “All
nitrates are soluble” So the 1st salt I use is Calcium Nitrate.
Next, I need to find “something‐sulfate” that is soluble. I also know that all
Group 1 salts are soluble.. So I can use Lithium Sulfate as my 2nd salt.
By reacting 2 salts, I’ll get what I want, which is Calcium Sulphate!!
Ca(NO3)2 + Li2SO4 → CaSO4 + 2LiNO3
By Reacting Carbonate with Acid
E.g. Reacting CaCO3 with Acids
K2CO3(s) + H2SO4(aq) →K2SO4(aq) + CO2(g) + H2O(l)
The same process is used as reaction of acid with metal, just that
carbon dioxide is produced. Carbon dioxide can be tested by bubbling
it into limewater which will turn limewater colourless to milky.
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Chemistry Dept/Grade9/First Term/2014
Imaduddin School
WORKSHEET on SALTS
6. Which pair of substances produces a precipitate when their
aqueous solutions are mixed?
MCQ Section
A) barium nitrate, silver nitrate
nitrate
1. In general, salts
A) are ionic compounds
B) contain hydrogen ions
C) contain hydroxide ions
D) turn litmus red
2. Which formula represents a salt?
A )KOH
B) KCl
C) CH3OH
A) CH3COOH
B) sodium chloride, barium
C) sodium nitrate, barium chloride D) sodium sulphate, barium
chloride
7. From which mixture can the underlined substance be obtained by
adding water, stirring and filtering?
A) calcium carbonate and sodium chloride
3. Which pair of substances produce a precipitate when their
aqueous solutions are mixed?
A) sodium chloride and barium nitrate
barium chloride
B) sodium nitrate and
C) sodium nitrate and silver nitrate
barium chloride
D) sodium sulphate and
4. Which salt can be prepared by an acid-alkali titration method?
5.
A) ammonium sulphate
B) copper(II) sulphate
C) iron(II) sulphate
D) zinc sulphate
The table shows properties of four chlorides. Which is
magnesium chloride?
B) copper(II) sulphate and sodium chloride
C) ethanoic acid and ethanol
D) iron and magnesium
8. Which two reagents could be used to prepare the insoluble salt
copper(II) carbonate?
A) CuO(s) + Na2CO3(aq)
B) CuO(s) + MgCO3(s)
C) CuSO4(aq) + Na2CO3(aq)
D) CuSO4(aq) + MgCO3(s)
9. The table shows the solubility of some salts of metal Y in cold
water.
What is metal Y?
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Chemistry Dept/Grade9/First Term/2014
Imaduddin School
A) barium
B) magnesium
C) lead
D) sodium
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10. What is the best way of making zinc carbonate?
A) Shake aq. zinc sulphate with aq. sodium carbonate.
B) Shake aq. zinc sulphate with solid calcium hydroxide and bubble in
carbon dioxide.
C) Shake solid zinc hydroxide with aq.sodium hydroxide and bubble in
carbon dioxide.
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D) Shake solid zinc sulphate and solid calcium carbonate with water.
Theory Section
11. Fertilisers are soluble salts containing one or more of the essential
elements required for plant growth.
(a) Ammonium chloride can be prepared by the reaction between
aqueous ammonia and hydrochloric acid. Write an ionic equation for
this reaction.
[1]
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(b) State suitable reagents and outline the experimental procedure
by which a pure sample of the fertiliser potassium chloride could be
prepared in the laboratory.
[4]
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.
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Page 4 of 4
Chemistry Dept/Grade9/First Term/2014
Imaduddin School