Acids Bases

Acids Bases
Bases
Examples of bases
Sodium Oxide
Potassium Oxide
Magnesium Oxide
Sodium Hydroxide
Potassium Hydroxide
Magnesium Hydroxide
Definition
A base is defined as a substance that
contains hydroxide ions (OHˉ) when
dissolved in water.
A base can also be defined as a
substance which accepts oxide or
hydroxide ions.
Solubility
Bases have different solubility
Most are insoluble in
water
Copper (II)
Oxide
Lead (II)
oxide
Bases which are
soluble are called
alkalis.
Sodium hydroxide
Calcium hydroxide
Properties
Alkalis have a bitter taste and
soapy feel
Alkalis turn red litmus blue.
Alkalis only show their
alkaline properties when
dissolved in water
This is because it is the
hydroxide ions that give alkalis
its properties
Alkalis, like acids, are also
good electrical conductors
Reactions
Neutralisation
Acid + Alkali => Salt + Water
E.g. Sodium Hydroxide +
Sulfuric Acid =>Sodium Sulfate
+ Water
Alkali + Ammonium salt =>
Ammonia + Water + Salt
Example: Sodium hydroxide +
Ammonium Chloride=> Sodium
Chloride + water + Ammonia
Test for Ammonia gas: If a colourless,
pungent gas that turns damp red litmus
paper blue is produced, the gas is ammonia.
Alkali(of metal A) + salt(of
metal B) => Metal B hydroxide
+ salt(of metal A)
Sodium hydroxide + Copper(II)
sulfate=> sodium sulfate +
Copper(II) hydroxide
If metal B hydroxide is soluble,
reaction will not take place
Applications
Ammonia Solution
Window cleaning solutions
Fertilisers
Sodium Hydroxide
Soaps and Detergents
Industrialcleaning detergents
Magnesium hydroxide
Toothpaste
Antacids
Calcium oxide
Neutralizing acidic soil
To make iron, concrete and cement
Acids
Definition
An acid is a substance that
dissociates to form hydrogen ions
when dissolved in water.
Classification
Organic acids contain carbon
and are found in living
things.
Lacitc Acid
Citric Acid
Ethanoic Acid
Inorganic acids do not contain carbon
and are commonly found in science
laborities.
Hydrochloric Acid
Sulfuric Acid
Reactions
Acids reacts with certain
metals to form a salt
and hydrogen gas
When a reactive metal, e.g. magnesium, is
added to an inorganic acid like hydrochloric
acid or sulfuric acid, effervescense will be
observed.
The reactive metal will
dissolve and the reaction
will give out heat.
The bubbles of gas
produced contain
hydrogen gas.
Hydrogen gas can be tested by
inserting a lighted splint into a test
tube. If the gas is hydrogen, the
splint will extinguish with a 'pop'
sound.
Unreactive metals like
copper and silver will not
react with acids
Acids react with all
carbonates to produce
a salt, water and
carbon dioxide gas.
When a carbonate compound, e.g. calcium
carbonate, is added to an inorganic acid like
hydrochloric acid or sulfuric acid,
effervescence will be observed.
The bubbles of gas
produced contain
carbon dioxide gas.
Carbon dioxide can be tested for by
bubbling the gas into calcium hydroxide
solution, also known as limewater. If the
gas is carbon dioxide, a white precipitate
will be observed in the calcium
hydroxide solution.
Acids react with metal
oxides/hydroxides to give a salt and
water
Types of oxides
Acidic Oxides
Are oxides of nonmetals
Most acidic oxides are soluble in water
and will give an acid(e.g. carbon
dioxide dissolves in water to give
carbonic acid)
Basic Oxides
Are oxides of metals
Most basic oxides are insoluble in
water except for a few(e.g. sodium
oxide, potassium oxide)
Amphoteric Oxides
Are metallic oxides that react with both
acids and bases to form a salt and
water
Examples:Aluminium oxide,
Lead(II) oxide, Zinc oxide
Neutral Oxides
Shows neither basic or acidic
properties
Examples: Water, Carbon
monoxide and nitric oxide
Properties
Acids taste sour.
Acids turn blue litmus red.
Acids are good electrolytes i.e.
they are good conductors of
electricity.
This is because the hydrogen ions are able to
move about freely in the acid and thus can
carry the electric charge
Applications
Hydrochloric Acid
Removes
Rust
Sulfuric Acid
Used in car
batteries
Nitric Acid
Making
explosives
Fertilizers
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