READY RECKONER FOR ACIDS, BASES
AND SALTS
Properties of Acids and Bases.
Acids
Bases / Alkalis
1
Acids are substances that give out H+ ions
when dissolved in water.
Bases are chemical opposites of acids. Bases
accept H+ ions and neutralize acids.
2
Acids will have pH less than 7. Lower the pH,
higher the acidic nature.
Bases will have pH greater than 7. Higher the pH,
greater the basic nature.
3
All acids are soluble in water. Acids show their
acidic nature only in the aqueous form (when
dissolved in water)
Bases could be soluble in water or could be
insoluble. Those bases that are soluble in water
are called ALKALIS.
4
There are two categories of acids. Strong and
weak acids.
There are two categories of bases. Strong and
weak bases.
5
Acids which are diluted with a lot of water are
called dilute acids. Acids with less water in
them are called concentrated acids.
Alkalis which are diluted with a lot of water are
called dilute alkalis. Alkalis with less water in them
are called concentrated Alkalis.
Both strong and weak acids can be either
concentrated or dilute.
Both strong and weak alkalis can be either
concentrated or dilute.
6
Some examples of strong acids are HCl,
H2SO4 and HNO3.
Some strong alkalis are NaOH, KOH, and Ca(OH)2.
7
An example of a weak acid is ethanoic acid,
CH3COOH.
An example of a weak base is aqueous ammonia
(NH3(aq)).
8
Acids turn Blue litmus paper red.
Alkalis turn red litmus paper blue.
9
Acids are corrosive. Handle them with care
and wear gloves and goggles while working
with acids.
Alkalis are corrosive too. Handle them with care
and wear gloves and goggles while working with
alkalis.
Chemical reactions of acids and bases
Acids
Bases / Alkalis
1
Dilute acids react with metals to form salt and
hydrogen gas.
Ammonia reacts with acids to form their respective
ammonium salts.
2
Dilute acids react with metal oxides to form
salt and water.
Ammonium salts react with alkalis to form salt,
water and ammonia gas.
3
Dilute acids react with metal hydroxides to
form salt and water too.
4
Dilute acids react with metal carbonates to
form salt, water and carbon dioxide.
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Important: Practise writing balanced chemical equations for the general reactions given in the previous
page. A sample of each one is given below. You can practise using HCl and H2SO4.
HNO3 or other acids need not be practised.
Reactions of acids with metals and bases - some examples
1. Acid + metal → salt + hydrogen gas.
2HCl + Mg → MgCl2 + H2
2. Acid + metal oxide → salt + water
3H2SO4 + Al2O3 → Al2(SO4)3 + 3 H2O
3. Acid + metal hydroxide → salt + water
2HCl + Ca(OH)2 → CaCl2 + H2O
4. Acid + metal carbonate → salt + water + carbon dioxide
3H2SO4 + Al2(CO3)3 → Al2(SO4)3 + 3H2O + 3CO2
Reactions of ammonia with acids; and ammonium salts with alkali - examples
1. Ammonia + acid → ammonium salt
2NH3 + H2SO4 → (NH4)2SO4
2. Ammonium salt + alkali → salt + water + ammonia gas.
NH4Cl + NaOH → NaCl + H2O + NH3
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Indicators
●
Indicators are substances that have different colour in different pH.
●
Some substances can even lose their smell in different pH conditions.
●
Some examples of indicators and their colours in acids and bases.
Table source: “Chemical Indicators Definition Types Examples.” GeeksforGeeks, 1 Sept. 2021, https://www.geeksforgeeks.org/chemical-indicators-definition-types-examples/.
Accessed 24 Aug. 2023.
Universal indicator colours
Image source: “Chemical Indicators Definition Types Examples.” GeeksforGeeks, 1 Sept. 2021, https://www.geeksforgeeks.org/chemical-indicators-definition-types-examples/.
Accessed 24 Aug. 2023.
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Oxides
Do you want to read more about oxides and their reactions? Click here: Oxides - Chemistry LibreTexts
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Salt Preparation
Solubility rules. (For repeated reference)
Type of salt
Solubility in water
Exceptions
1
All group I salts
soluble
none
2
All nitrate salts
soluble
none
3
All ammonium salts
soluble
none
4
Most halides
soluble
Silver halides and lead(II) halides
5
Most sulfates
soluble
Calcium sulfate (CaSO4)
Barium sulfate (BaSO4)
Lead sulfate (PbSO4)
6
Most carbonates
INSOLUBLE
Group I carbonates
Ammonium carbonate
7
Most hydroxides
INSOLUBLE
Group I hydroxides
Ammonium hydroxide (aqueous ammonia)
Lower group II sulfates (their solubility
increases as we go down the group).
What are salts?
● Salts are neutralization products of bases and acids.
● We get salts when the metal of a base / alkali replaces the H+ in an acid.
● Salts obtained through the process of crystallization have water of crystallization. Example:
CuSO4.5H2O.
● Different acids form different salts.
○ Hydrochloric acid always produces chloride salts.
○ Sulfuric acid always produces sulfates.
○ Nitric acid always produces nitrates.
○ Ethanoic acid produces ethanoates.
Salts are of two types.
● Soluble salts
● Insoluble salts
Methods to prepare soluble salts.
Method 1: Acid + Metal (moderately reactive metals)
Salts of Magnesium, Aluminium, Zinc, Iron and Tin (MAZIT) can be prepared by this method.
Procedure. (preparing Magnesium chloride)
● Take a beaker containing dilute hydrochloric acid.
● Add magnesium powder till the bubbles stop to form.
● Mg + 2HCl → MgCl2 + H2
● Filter off the excess Magnesium powder added.
● Take the filtrate and subject it to crystallization. Pure crystals of Magnesium chloride are formed.
● Filter off the pure magnesium chloride crystals from the saturated solution using a filter paper.
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Method 2: Acid + insoluble metal oxide (less reactive metals)
Salts below hydrogen in the reactivity series can be prepared using this method.
Procedure: (preparing copper(II) sulfate).
● Take a beaker containing dilute sulfuric acid.
● Add copper oxide powder till excess unreacted powder settles at the bottom of the beaker.
● CuO + H2SO4 → CuSO4 + H2O
● Heat if necessary to allow the reaction to speed up the reaction.
● After cooling the mixture, filter off the excess copper oxide.
● Subject the filtrate to crystallization. Pure crystals of copper(II) sulfate are formed.
● Filter off the crystals formed from the saturated solution.
Method 3: Acid + insoluble metal carbonate
All metal salts can be prepared using this method provided that its precursor is an insoluble metal
carbonate.
● Procedure: (preparing calcium nitrate salt).
● Take a beaker containing dilute nitric acid.
● Add calcium carbonate powder until effervescence stops.
● CaCO3 + 2 HNO3 → Ca(NO3)2 + H,O + CO2
● Filter off the excess calcium carbonate.
● Subject the filtrate to crystallization. Pure crystals of calcium nitrate forms.
● Filter off the pure calcium nitrate from its saturated solution.
Method 4: Acid + metal hydroxide (titration method)
Salts of highly reactive metals like Na and K and of the group I metals can be prepared safely by this
method.
Procedure (preparing potassium chloride)
● Take a known volume of potassium hydroxide solution in a conical flask.
● Add a few drops of phenolphthalein indicator. The KOH solution turns pink.
● Using a burette, add dilute hydrochloric acid to the conical flask until the KOH solution just turns
colorless.
● KOH + HCl → KCl + H2O
● Note down the volume of dilute HCl that was required to neutralize the aqueous KOH.
● Repeat the titration without phenolphthalein indicator.
● Crystallize the neutralized solution. Crystals of KCl will form.
● Filter the KCl crystals from the saturated solution of KCl.
Preparing an Insoluble salt by precipitation method.
(Only one method)
Procedure (preparing Silver chloride).
●
●
●
●
●
●
Take aqueous silver nitrate solution in a beaker.
Mix it to a solution of sodium chloride present in another beaker.
AgNO3 + NaCl → AgCl + NaNO3
Filter and collect the precipitate formed.
Wash the precipitate with distilled water to remove any soluble impurities.
Dry the precipitate of silver chloride in the folds of a filter paper.
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Detecting cations.(simplified table)
S.No.
Cations
Few drops of
aqueous
NaOH
Excess
aqueous
NaOH
Few drops of
aqueous NH3
Excess
aqueous NH3
1
Calcium, Ca2+
White ppt
insoluble
No reaction
No reaction
2
Zinc(II), Zn2+
White ppt
soluble
White ppt
soluble
3
Iron (II) ,Fe2+
Green ppt
insoluble
Green ppt
insoluble
4
Iron(III), Fe3+
Reddish brown
ppt
insoluble
Reddish brown
ppt
insoluble
5
Copper(II) Cu2+
Pale blue ppt
insoluble
Pale blue ppt
6
Ammonium, NH4+
Add aqueous NaOH and warm.
Soluble
Forms a deep
blue solution.
Pungent smelling gas which
turns damp red litmus paper blue
evolves.
Detecting anions
S.no.
Experiment
1
To the substance being tested, add
dilute acid (HCl / H2SO4 / HNO3)
Effervescence (bubbles)
(fizzing)
Carbonate is present
2
To the substance being tested, add
dilute nitric acid and then add
aqueous silver nitrate.
White ppt
Chloride is present
Cream ppt
Bromide is present
4
To the substance being tested, add
dilute nitric acid and then add
aqueous barium nitrate
White ppt
Sulfate is present
5
To the substance being tested, add
aqueous sodium hydroxide and
aluminum foil and warm the
mixture.
Pungent smelling gas which
turns damp red litmus paper
blue evolves.
Nitrate is present.
3
observation
inference
Detecting gases
S.no.
Experiment
observation
inference
1
Introduce a glowing splint.
Splint lights up
Gas is oxygen.
2
Introduce a burning splint.
Fire goes off with a squeaky pop.
Gas is hydrogen.
3
Introduce a damp red litmus
paper.
Gas has a pungent smell. It turns
damp red litmus paper blue.
Gas is ammonia.
4
Introduce a damp litmus paper.
Litmus paper is bleached (turns
white).
Gas is chlorine.
5.
Pass the gas that evolves
through lime water.
Lime water turns milky (Lime
water is aqueous calcium
hydroxide).
Gas is carbon dioxide.
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