Chapter-2-Acids-Bases SCIENCE BOOK BY YOUTUBE

Your
Jay Bhaiya
Your
Jay Bhaiya
Acids, Bases
Acids, Bases
and Salts
and Salts
Class 10 (Science)
Chapter 2
Chapter 2
Made for You with
by Jay Rana
Handwritten
Notes

What is an Acid?
H ion
Gives H ions (protons)
+
+
Acids are the substance that are sour in taste, turns bl
ue litmus paper red, and gives
H+ ions (protons) in their aqueous solution.
HCl (Hydrochloric acid)
Examples of acids
HNO (Nitric acid)
H SO (Sulphuric acid)
3
2 4
Sour in taste Turns blue litmus paper red
Knords Learning

What is a Base?
Bitter in taste Turns red litmus paper blue
Bases are the substance that are bitter in taste, turns red litmus paper blue, and gives
OH- ions (hydroxide ions) in their aqueous solution.
NaOH (Sodium hydroxide or caustic soda)
Examples of bases
Ca(OH) (Calcium hydroxide or slaked lime)
KOH (Potassium hydroxide)
2
OH ion
Gives OH ions
-
-
Knords Learning

What are Alkalis?
The bases that are soluble in water are called alkalis.
All bases do not dissolve in water. An alkali is a base that dissolves in water.
Remember:
Knords Learning

Concentrated acid
Dilute acid
Concentrated acids have a higher concentration of acid molecules
compared to the solvent.
Dilute acids have a lower concentration of acid molecules compared
to solvent.
Examples
Concentrated sulfuric acid
Concentrated hydrochloric acid
Examples
Dilute sulfuric acid
Dilute hydrochloric acid
Less acid
molecules
More acid
molecules
They are generally less reactive and safer to handle.
This means they are more potent and can react more vigorously.
Knords Learning

Concentrated base
Dilute base
Concentrated bases have a higher con
centration of base
molecules compared to the solvent.
Examples
Concentrated NaOH
Concentrated KOH
Dilute bases have a lower concentration of base molecules compared
to solvent.
Examples
Dilute NaOH
Dilute KOH
Less base
molecules
More base
molecules
Knords Learning

Acid-Base indicators
1) Natural indicators
These are indicators derived from naturally occurring sources.
Acid-base indicators are substances that change their color or smell (odour) in the
presence of an acid or a base.
Examples
Litmus solution (a purple dye
extracted from lichen plant)
Turmeric Red cabbage leaves
There are basically 3 types of indicators.
1) Natural indicators
2) Synthetic indicators and
3) Olfactory indicators
Knords Learning

2) Synthetic indicators
3) Olfactory indicators
These are indicators artificially created in laboratories through chemical synthesis.
These are substances that change their smell (odour) upon contact with acids or bases.
Methyl orange Phenolphthalein
Vanilla essence Clove oil
Examples
Examples
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Chemical properties of Acids and Bases
Reaction with Metals
1.
Reaction with Metal Carbonates and Metal Hydrogencarbonates
2.
How do Acids and Bases react with each other?
3.
Reaction of Metallic Oxides with Acids
4.
Reaction of Non-metallic Oxides with Bases
5.
Knords Learning

1) Reaction with Metals
Acids and bases reacts with metal to form a compound called salt and releases
hydrogen gas.
H SO + Zn
2
ZnSO + H
4 4 2
+ +
Acid/Base Salt
Metal Hydrogen gas
2NaOH + Zn Na ZnO + H
2 2
2
(Sodium zincate)
Acid + Metal:
Base + Metal:
Examples
Knords Learning

Acid
2) Reaction with Metal Carbonates and Metal Hydrogencarbonates
Acids react with metal carbonate/metal hydrogencarbonate to give a corresponding
salt, carbon dioxide and water.
Salt
Metal carbonate/metal
hydrogencarbonate
CO2
+ + +
Water
2HCl + Na CO 2NaCl + CO + H O
2
2
2 3
Acid + Metal carbonate:
HCl + NaHCO NaCl + CO + H O
2
2
3
Acid + Metal Hydrogencarbonate:
Examples Knords Learning

3) How do Acids and Bases react with each other?
Acid and base reacts with each other to form a salt and water.
+ +
Acid Salt
Base Water
The reaction between an acid and a base to give a salt and water is known as a
neutralisation reaction.
HCl + NaOH NaCl + H O
2
For example
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4) Reaction of Metallic Oxides with Acids
Metal oxide reacts with acid to give a corresponding salt and water.
+ +
Acid Salt Water
Metal oxide
CuO + 2HCl CuCl + H O
2
2
Since metallic oxides react with acids to give salts and water, similar to the reaction of
a base with an acid, metallic oxides are said to be basic oxides. In other words, metal
oxides are basic in nature.
Example
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5) Reaction of Non-metallic Oxides with Bases
Non-metallic oxide reacts with base to give a corresponding salt and water.
+ +
Base Salt
Non-metallic oxide
CO + Ca(OH) CaCO + H O
2
3
Since this is similar to the reaction between a acid and a base, we can conclude that
nonmetallic oxides are acidic in nature.
Water
2
2
Example
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What do all acids have in common?
All acids have Hydrogen ion (H ion) as a cation.
Acids gives Hydrogen ions (H ions) in a solution.
The H ions present in an acids are responsible
for their acidic properties.
HCl contains H ion and Cl ion.
H SO contains H ion and SO ion.
4
2-
+
+
+
+
+
-
4
2
H ion
+
Examples
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All bases have Hydroxide ion (OH ion) as an anion.
Bases gives Hydroxide ions (OH ions) in a solution.
The OH ions present in a bases are responsible for
their basic properties.
NaOH contains Na ion and OH ion.
Ca(OH) contains Ca ion and OH ions.
2
2+ -
-
+
-
-
-
What do all bases have in common?
OH ion
-
Examples
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What happens to an Acid or a Base in a water solution?
For example:
Acids: Acid have H ion in it. So when the acid reacts with water, this H ion reacts with
water to form H O ion.
3
+
+ +
HCl + H O H O + Cl
3
2
-
+
Hydronium ion
Hydrogen ions cannot exist alone, but they exist after combining with water molecules.
H + H O H O
3
2
+
+
Thus hydrogen ions must always be shown as H (aq) or H O (hydronium ion).
+ +
3
Bases: Bases generate hydroxide ions (OH ions) in water.
-
For example: NaOH(s) Na (aq) + OH (aq)
2 -
+
H O
OR
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How strong are acid or base solutions?
Universal indicators
The strength of acid or base can be determined by the
concentration of H and OH ions present in the
solution. This can be done by using universal indicators.
-
+
Universal indicator is a mixture of several indicators
which shows different colours at different
concentrations of hydrogen ions in a solution.
pH paper
Example Knords Learning

pH scale
pH is simply a number which indicates the acidic or basic nature of a solution.
Acidic nature increasing Basic nature increasing
Neutral
7
Increase in H ion concentration Decrease in H ion concentration
14
0
H
OH
-
+
+ +
If a substance has a pH value greater than 7, then it is basic.
If a substance has a pH value less than 7, then it is acidic.
If a substance has a pH value equals to 7, then it is neutral.
The amount of H ions and OH ions determines the strength of acid and base respectively.
-
+
More OH ions, strong base. Less OH ions, weak base.
More H ions, strong acid. Less H ions, weak acid.
-
+ +
-
Remember:
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pH of some common substances
pH paper shows different colors based on acidity and basicity of the substance.
Gastric
juice
(about 1.2)
Lemon
juice
(about 2.2)
Pure water,
blood
(7.4)
Milk of
magnesia
(10)
Sodium
hydroxide
solution
(about 14)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
NaOH(aq)
Knords Learning

Strong acids and weak acids
Strong acid:
Weak acid:
Strong acids are those acids that dissociates
completely in their aqueous solution.
Strong acids releases more H ions in their
aqueous solution.
+
For example: H SO , HCl
2 4
Weak acids are those acids that dissociates partially
in their aqueous solution.
Weak acids releases less H ions in their
aqueous solution.
+
For example: CH COOH (acetic acid)
3
More
H ions
+
Less
H ions
+
Knords Learning

Strong bases and weak bases
Strong base:
Weak base:
Strong bases are those bases that dissociates
completely in their aqueous solution.
Strong bases r
eleases more OH ions in their
aqueous solution.
-
Weak bases are those bases that dissociates partially
in their aqueous solution.
Weak bases releases less OH ions in their
aqueous solution.
-
For example: NH (ammonia)
3
For example: NaOH
More
OH ions
-
Less
OH ions
-
Knords Learning

Importance of pH in everyday life
1) Our body works within the pH range of 7.0 to 7.8.
Living organisms can survive only in a narrow
range of pH change.
2) If pH of rain water is less than 5.6, it is called acid rain.
When acid rain flows into the rivers, it
lowers the pH of the river water.
The survival of aquatic life in such rivers
becomes difficult.
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3) Our stomach produces hydrochloric acid (HCl).
It helps in the digestion of food without
harming the stomach.
During indigestion the stomach produces too
much acid and this causes pain and irritation.
To get rid of this pain, people use antacids
(bases) like Magnesium hydroxide (Milk of
magnesia).
4) Plants require a specific pH range for their healthy growth.
Plants grow better in the soil that has
suitable pH for that growth.
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5) Tooth decay starts when the pH of the mouth is lower than 5.5.
Bacteria present in the mouth produce acids
by degradation of sugar and food particles
remaining in the mouth after eating.
The best way to prevent this is to clean the
mouth after eating food and by using
toothpastes which are generally basic.
6) Bee-sting leaves a formic acid which causes pain and irritation.
We can get relief by using mild base like
baking soda on the stung area.
7) Stinging hair of nettle leaves inject methanoic acid
causing burning pain.
We can get relief by rubbing the area with
the leaf of the dock plant (which is basic in
nature).
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Vinegar
Orange
Tamarind
Tomato
Sour milk (curd)
Lemon
Ant sting
Nettle sting
Some naturally occurring acids
Natural source Acid
Acetic acid
Citric acid
Tartaric acid
Oxalic acid
Lactic acid
Citric acid
Methanoic acid
Methanoic acid
Knords Learning

What are Salts?
Salt is an ionic compound that is formed by
the neutralization reaction.
Neutralisation reaction
The reaction between an acid and a base to give a salt and water is known as a
HCl + NaOH NaCl + H O
2
For example
+ +
Salt
Base Water
Acid
Knords Learning

pH of salts
+ +
+ +
Strong acid Weak base Acidic salt (pH < 7) Water
Weak acid Strong base Basic salt (pH > 7) Water
Salts of a strong acid and weak base are acidic with pH value less than 7.
Salts of a weak acid and strong base are basic with pH value greater than 7.
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+ +
Strong acid Neutral salt (pH = 7) Water
Strong base
Salts of a strong acid and strong base are neutral with pH value of 7.
For example: NaCl is a neutral salt made of strong acid (HCl) and strong base (NaOH).
Knords Learning

Chemicals from common salt
Sodium hydroxide (NaOH)
1.
Bleaching powder (CaOCl )
2.
Baking soda (NaHCO )
3.
Washing soda (Na CO .10H O)
4.
Plaster of Paris (CaSO . H O)
5.
2
3
2 3
4
1
2
_
2
2
Knords Learning

1) Sodium hydroxide (NaOH)
When electricity is passed through an aqueous
solution of sodium chloride (called brine), it
decomposes to form sodium hydroxide.
The process is called the chlor-alkali process.
2NaCl + 2H O 2NaOH + Cl + H
2
Formation reaction
2
2
Uses of Sodium hydroxide
Used for
de-greasing metals
Used in soaps
and detergents
Used in
Paper making
Used in making
artificial fibers
Knords Learning

2) Bleaching powder (CaOCl )
2
Bleaching powder is produced by the action of chlorine on dry slaked lime [Ca(OH) ].
2
Ca(OH) + Cl CaOCl + H O
2
2
2 2
Uses of Bleaching powder
Bleaching cotton
and linen
Bleaching wood pulp
in paper factories
Used as oxidizing
agent in industries
To make drinking
water germ free
Formation reaction
Knords Learning

3) Baking soda (NaHCO )
3
Baking soda is produced when salt reacts with water, carbon dioxide and ammonia.
NaCl + H O + CO + NH NH Cl + NaHCO3
2
2 4
Uses of Baking soda
Making baking
powder
Used in antacids for
stomach acidity
3
On heating, it decomposes to give sodium carbonate with the evolution of carbon dioxide.
2NaHCO Na CO + H O + CO
3
2
3 2 2
Δ
Baking soda (or sodium-
hydrogencarbonate)
Used in soda-acid
fire extinguishers
Formation reaction
Knords Learning

Na CO + 10H O
2 3
4) Washing soda (Na CO .10H O)
3
2 2
Washing soda is obtained by recrystallisation of sodium carbonate (Na CO ).
Uses of washing soda
Used in glass,
soap and paper
industries
Used in
manufacturing
of borax
Used as
cleaning agent for
domestic purpose
Used for removing
permanent
hardness of water
2 3
Na CO .10H O
3 2
2
2
Washing soda
Sodium carbonate
Formation reaction
Knords Learning

When Plaster of Paris is mixed with water, it changes to gypsum once again giving a hard
solid mass.
5) Plaster of Paris (CaSO . H O)
4 2
1
2
_
When gypsum is heated at 373 K (100 deg C),
it loses water molecules and becomes calcium
sulphate hemihydrate, which is called Plaster
of Paris.
CaSO . 2H O
2
4
100 °C
CaSO . H O + 1 H O
2
4
1
2
_ 1
2
_
2
(Plaster of Paris)
(Gypsum)
CaSO . 2H O
2
4
(Gypsum)
CaSO . H O + 1 H O
2
4
1
2
_ 1
2
_
2
(Plaster of Paris)
(POP + water) (Gypsum)
Formation reaction
Knords Learning

Uses of Plaster of Paris
Used to support
fractured bones
Used in toys,
statues and
decorations
Used in making
surface smooth
Knords Learning

Water of crystallisation is the fixed number of water molecules present in one formula
unit of a salt.
Water of crystallisation
For example
Gypsum
Washing soda
(CaSO . 2H O)
2
4
(Na CO .10H O)
3 2
2
One formula unit of Washing soda contains 10 molecules of water as a water of
crystallisation.
One formula unit of Gypsum contains 2 molecules of water as a water of
crystallisation.
Knords Learning

Sample
solution
Red litmus
solution/paper
Blue litmus
solution/paper
Phenolphthalein
solution
Methyl orange
solution
HCl
No change
(remains red)
Turns red
No change
(remains colorless)
Turns pinkish
red
H SO
HNO
CH COOH
NaOH
Turns blue
No change
(remains blue)
Turns pinkish red Turns yellow
Ca(OH)
KOH
Mg(OH)
NH OH
2 4
3
3
2
2
4
Acids
Bases
Knords Learning

Blue litmus: It turns red in acid.
Red litmus: It turns blue in base.
Phenolphthalein: It turns pinkish red in bases.
Methyl orange: It turns pinkish red in acids, and turns yellow in bases.
Knords Learning

Smell remains as it is. Smell disappears.
These onion-treated strips
has a sulfur compounds.
dil. HCl
(acid)
dil. NaOH
(base)
Observation Observation
Onion
Onion treated strip
(acidic)
Onion treated strip
(acidic)
Knords Learning

dil. HCl
(acid)
Vanilla essence
Vanilla essence
dil. NaOH
(base)
(acidic)
Smell remains as it is. Smell disappears.
Observation Observation
/ clove oil Vanilla essence
(acidic)
/ clove oil
/ clove oil
Knords Learning

Remember:
Why this happened?
- Onion, vanilla and clove oil are the olfactory indicators that are slightly acidic in nature.
- When these acidic olfactory indicators reacts with acids, their smell remains as it is,
and when they reacts with base, its smell disappears.
Olfactory indicators (like onion, vanilla, clove oil) + Acid = Smell remains as it is
Olfactory indicators (like onion, vanilla, clove oil) + Base = Smell disappears
Knords Learning

Unknown substance
Vanilla essence
Que: When a vanilla essence is added to the unknown substance, its smell disappears.
Identify whether the unknown substance is acidic or basic.
Question
Ans: - Vanilla essence is an olfactory indicator which is slightly acidic in nature. And it loses
its smell only when it reacts with the base.
- So the unknown substance is basic in nature.
Knords Learning

Activity 2.3
Reaction involved: Zn + H SO4
ZnSO + H
4
2 2

Que: What will you observe when zinc granules reacts with dilute sulphuric acid?
Ans: - When zinc granules react with dilute sulfuric acid, you will observe the evolution of
hydrogen gas from the surface of zinc granules.
- Also these reactions are exothermic reactions, meaning heat will liberate during this
reactions.
- The chemical equation for the reaction is as follows:
Questions
Zn + H SO4
ZnSO + H
4
2 2
Knords Learning

Que: Why do we hear the pop sound when a burning candle is kept near the exit of the
delivery tube in the above activity?
Ans: - The pop sound occurs when the burning candle is brought near the exit of the delivery
tube because the hydrogen gas being released from the reaction between the zinc and the
acid combusts upon contact with the flame of the candle.
- This combustion reaction produces a small explosion, resulting in the pop sound.
Que: What happens when CH3COOH (acetic acid) is used in the above activity?
Ans: - CH3COOH (acetic acid) is a weak acid. And due to its weaker acidic properties, the
reaction between CH3COOH and zinc will proceed at a slower rate and produce less hydrogen
gas.
- Therefore, the rate of bubble formation and the intensity of the reaction will be lower
compared to strong acids.
Knords Learning

Activity 2.4
Reaction involved: Zn + NaOH Na ZnO + H
2 2
2
2
(Sodium zincate)

Que: What happens when a metal reacts with a base? Give one example.
Ans: - When a metal reacts with a base, it undergoes a displacement reaction and forms a
salt and a liberates a hydrogen gas.
- For example: When granulated zinc metal reacts with sodium hydroxide solution, a salt
(sodium zincate) is formed and a hydrogen gas is evolved.
- The reaction can be represented as:
Questions
Zn + NaOH Na ZnO + H
2 2
2
2
(Sodium zincate)
Knords Learning

Activity 2.5
Reaction involved: Na CO + HCl NaCl + H O + CO2
2
2
Test tube A:
Test tube B:
2 3
2
NaHCO + HCl NaCl + H O + CO2
2
3
On passing the carbon dioxide gas through lime water;
Ca(OH) + CO CaCO (s) + H O
2
3
2 2
(Lime water) (White precipitate)

Que: What happens when a metal carbonates reacts with acids? Explain with an example.
Ans: - The metal carbonate reacts with the acid, it forms the corresponding salt of the
metal, water, and carbon dioxide gas.
- Here is an example of the reaction between sodium carbonate (metal carbonate) and
hydrochloric acid.
Questions
Na CO + HCl NaCl + H O + CO2
2
2
2 3
2
Knords Learning

Que: What happens when the CO2 gas is passed over the calcium hydroxide solution in
the test tube? Explain with a chemical reaction.
Ans: - When carbon dioxide gas is passed over calcium hydroxide solution [Ca(OH)2], it reacts
to form calcium carbonate (CaCO3) and water. The calcium carbonate appears as a solid white
precipitate in the test tube. The chemical equation for this reaction is as follows;
Ca(OH) + CO CaCO (s) + H O
2
3
2 2
(Lime water) (White precipitate)
Knords Learning

Activity 2.6
Phenolphthalein HCl NaOH
NaOH

Phenolphthalein + Base = Pink color
Phenolphthalein + Acid = Colorless
- In the above activity, the phenolphthalein reacts with base (NaOH) and it turns pink in
color. But when acid (HCl) is added to this test tube, it again turns colorless.
- And again when base (NaOH) is added to this test tube, the solution turns to pink again.
- So in the above activity, we have observed that the effect of a base is nullified by an
acid and vice-versa.
- The reaction between an acid and a base to give a salt and water is known as a
Side note: Phenolphthalein is an indicator which is colorless.
What have you learnt?
Knords Learning

Activity 2.7
Reaction involved: CuO(s) + HCl(aq) CuCl (aq) + H O(l)
2
2
2
CuO
HCl
CuCl (aq)
2
(Blue - green
color)

Que: What happens when a metal oxides reacts with acids? Explain with an example.
Ans: - The metal oxide reacts with the acid to form the corresponding salt of the metal and
water.
- Here is an example of the reaction between copper oxide (metal oxide) and hydrochloric acid.
Questions
CuO(s) + HCl(aq) CuCl (aq) + H O(l)
2
2
2
- During this reaction, the color of the solution turns blue-green, which indicated the
presence of copper chloride (CuCl2).
Knords Learning

Que: When dilute hydrochloric acid is added to the metal oxide, it forms salt and water.
Identify whether the metal oxide is acidic or basic.
Ans: - When dilute hydrochloric acid is added to a metal oxide and it forms salt and water,
which is similar to the acid reacting with base to form salt and water.
Acid + Base = Salt + water
Acid + Metal oxide = Salt + water
- As the metal oxide is capable of neutralizing the acid, it is considered basic in nature.
Knords Learning

Observations
The bulb will start glowing in the case of acids (i.e. HCl and H2SO4).
The bulb will not glow in the case of a glucose and alcohol.
- Glowing of bulb indicates that there is a flow of electric current through the solution.
- The electric current is carried through the acidic solution by ions.
All the bases produces OH- ions i
n solution.
All the acids produces H+ ions in solution.
Knords Learning

Que: Why does an aqueous solution of an acid conduct electricity?
Ans: - An aqueous solution of an acid conducts electricity because acids ionize or dissociate in
water, producing ions that can carry electric charge.
- Acids produces hydrogen ions (H+ ions) in solution. These hydrogen ions can carry electric
charge through the solution.
Questions
Knords Learning

Activity 2.9
Reaction involved: NaCl(s) + H SO (l) Na SO (s) + HCl(g)
2
2 2 4 4
2

Observations
Dry HCl gas is an acidic gas and it will come out from the delivery tube.
When dry blue litmus paper is brought near this HCl gas, the litmus will not turn red.
But when moist blue litmus paper is brought near this HCl gas, the litmus will turn red.
The separation of H+ ion from HCl molecules cannot occur in the absence of water.
This experiment suggests that hydrogen ions (H+ ions) in HCl are produced in the
presence of water.
Hydrogen ions cannot exist alone, but they exist after combining with water molecules.
Thus hydrogen ions must always be shown as H+ (aq) or hydronium ion (H3O+).
Knords Learning

Que: Why does dry HCl gas not change the colour of the dry litmus paper?
Ans: - Dry HCl gas does not change the color of dry litmus paper because it does not contain
water.
- Litmus paper changes color in the presence of acidic or basic solutions due to the presence of
water which is responsible for ionization of acids or bases.
- Dry HCl gas lacks the water needed for ionization, so it cannot produce hydrogen ions (H+)
responsible for acidic properties. Therefore, it does not react with dry litmus paper.
Questions
Knords Learning

Concentrated H SO
Water
Activity 2.10
2 4

Observation
The process of dissolving an acid or a base in water is a highly exothermic one.
Que: While diluting an acid, why is it recommended that the acid should be added to
water and not water to the acid?
Ans: - It is recommended to add acid to water rather than water to acid while diluting because
adding water to acid can result in a highly exothermic reaction, potentially causing the solution
to splash or boil, leading to dangerous accidents.
- The glass container may also break due to excessive local heating. So it is always
recommended to add acid to the water.
Questions
Knords Learning

Activity 2.11
Green 7.4 Basic
Yellow-green
Orange
Green
Dark blue
Red
Yellow
Orange
Orange
Yellow-green
6 Acidic
2.5 Acidic
6 Acidic
5.5 Acidic
5 Acidic
4 Acidic
6.5 to 8 Acidic/Basic
14 Basic
0 Acidic

Soil
Activity 2.12
Acidic soil
(pH between 6 to 7)
pH paper
Water
Filtrate

Que: Under what soil condition do you think a farmer would treat the soil of his fields
with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium
carbonate)?
Ans: - A farmer would treat the soil of his fields with quicklime (calcium oxide), slaked lime
(calcium hydroxide), or chalk (calcium carbonate) under acidic soil conditions.
- These substances are bases that will neutralize the acidity and raise the pH of the soil.
Questions
Knords Learning

Salts Chemical formulae Base used Acid used
Potassium sulphate K SO KOH H SO
Sodium sulphate Na SO NaOH H SO
Calcium sulphate CaSO Ca(OH) H SO
Magnesium sulphate MgSO Mg(OH) H SO
Copper sulphate CuSO Cu(OH) H SO
Sodium chloride NaCl NaOH HCl
Sodium nitrate NaNO NaOH HNO
Sodium carbonate Na CO NaOH H CO
Ammonium chloride NH Cl NH OH HCl
Sulphate salts
Chloride salts
Sodium salts
2 4
2 4
4
4
4
3
3
2
4
2
2
2
4
2 3
3
2 4
2 4
2 4
2 4
2 4
Trick: Aage “OH” add karo to base milega, aur piche “H” add karo to acid milega
Knords Learning

Salt sample
Distilled water
Activity 2.14

Salts pH Base used Acid used
Sodium chloride pH = 7 (Neutral salt) NaOH HCl
Potassium nitrate pH = 7 (Neutral salt) KOH HNO
Aluminum chloride pH < 7 (Acidic salt) Al(OH) HCl
Zinc sulphate pH < 7 (Acidic salt) Zn(OH) H SO
Copper sulphate pH < 7 (Acidic salt) Cu(OH) H SO
Sodium acetate pH > 7 (Basic salt) NaOH CH COOH
Sodium carbonate pH > 7 (Basic salt) NaOH H CO
Sodium hydrogencarbonate pH > 7 (Basic salt) NaOH H CO
3
2
2
2 3
3
2 4
2 4
3
3
2
Neutral salt
Basic salts
Acidic salts
- Salts of a strong acid and a strong base are neutral (pH value of 7).
- Salts of a strong acid and weak base are acidic (pH value less than 7).
- Salts of a strong base and weak acid are basic (pH value more than 7).
Knords Learning

Observation
Heating copper sulfate changes its color from blue to white due to the loss of water
molecules.
Water droplets are formed in the boiling tube from the released water vapor during
heating.
Adding water to the heated copper sulfate restores its blue color as it rehydrates
to form hydrated copper sulfate.
- The salts contains some water molecules in it; for example, the formula of copper
sulfate is CuSO4 . 5H2O. So copper sulfate has 5 molecules of water.
- This fixed number of water molecules (5H2O) present in one formula unit of a copper
sulfate is the water of crystallisation.
Knords Learning

Chapter-2-Acids-Bases SCIENCE BOOK BY YOUTUBE

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Chapter-2-Acids-Bases SCIENCE BOOK BY YOUTUBE