Acids and Bases
Grade- 9
Table of Contents
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Definitions of Acid and Bases
Properties with example and Explanation
pH scale
Picture Examples
Definition of Acid.
• An acid generates H+ ions in a solution.
Or
• An acid is a proton donor.
Properties of acids
• Acids are good conductors of electricity.
• They are corrosive in nature.
• When reacted with metals, acid substances
produce hydrogen gas.
• Always, their pH values are less than 7.
• Acids are sour-tasting substances.
Examples
Product A
• Feature 1
• Feature 2
• Feature 3
Explanation .
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HCl( aq ) ⇆ H + ( aq )+ Cl −( aq )
In Hydrochloric acid, hydrogen ions and Chloride ions
recombine to form Hydrochloric acid molecules. The double
arrow signifies that at any given instant, 100 percent of
Hydrochloric acid molecules dissociate into hydrogen ions and
chloride ions.
CH 3COOH( aq ) ⇆ H + ( aq )+CH 3 COO −( aq )
In acetic acid, hydrogen ions and acetate ions recombine to
form acetic acid molecules. The double arrow signifies that at
any given instant, less than 5 percent of acetic acid molecules
dissociate into hydrogen ions and acetate ions.
Definition of Bases.
• A base generates an OH- ion in its solution.
Or
• a base is a proton acceptor.
Properties of Bases
• Bases are found to have a soapy texture when we touch
them.
•Bases act as good conductors of electricity in their aqueous
solutions
•Always, the pH values corresponding to the bases are
greater than 7.
•Bases are bitter-tasting substances, having the ability to
turn red litmus paper into blue.
Examples
Explanation.
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NaOH( aq ) + H 2 O ( l ) ⇆ Na + ( aq ) + OH − ( aq )
Sodium Hydroxide is a strong base, and although it have
OH − ions in its formula, it produces the ion on reaction with
water
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NH 3 ( aq ) + H 2 O ( l ) ⇆ NH 4 + ( aq ) + OH − ( aq )
Ammonia (NH 3 ) is a weak base, and although it does not have
OH − ions in its formula, it produces the ion on reaction with water
Definition of pH
pH is a measure of how acidic/basic water is. The
range goes from 0 - 14, with 7 being neutral. pH’s of
less than 7 indicate acidity, whereas a pH of greater
than 7 indicates a base. pH is really a measure of
the relative amount of free hydrogen and hydroxyl
ions in the water.
pH scale.
Example Acid from daily life.
Banana
pH = 4.7
Most common fruit in all
over the world.
Its pH shows it’s a weak acid.
Vinegar
pH = 3.4
Weak Acidic solution
It is an organic acid which we
mostly use in our salads.
Example Acid from daily life.
Yogurt
pH = 4.4
It is weak acidic. And we use it every
day in our break fast. Addition of
flavors & preservatives make it more
acidic.
Lemon Juice
pH = 2
Strong Acidic solution
All citrus fruits are acidic.
Example Acid from daily life.
Brown Sugar
pH = 6.5
It is Slightly Acidic .
It is an organic compound.
Which is actually raw form of
white sugar.
Example Bases from daily life.
Milk of Magnesia
pH = 10.5
Weak basic solution.
It is medication use to treat heart
burn, up stomach and acidity.
Oven cleaner
pH = 11-13
Weak basic solution
It has great power to cut trough
tough grease and grime.
Example Bases from daily life.
Drain cleaner
pH = 14
Strong basic in nature
That is why it is used to clean
drain and kill germs.
Soap
pH = 9
Weak Acidic
It is an organic compound
which is slippery in nature.
Example Bases from daily life.
Baking Powder
pH = 9
Mildly basic in nature
It is save food additive and
we use it daily in many baked
items in our food.
Thanks
Do you have any questions?