Explanation
Laboratory preparation-By heating ammonium chloride and Calcium hydroxide 2NH4CI+Ca(OH)2^CaCl2+2H2O+2NH3
Formed ammonia is passed through quick lime(Calcium oxide) to remove water
Due to less density Ammonia collected by inverted gas jar.
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Properties
Easily soluble in water to form Ammonium hydroxide.
Pungent smell
Red litmus paper turn blue due to basic character
Density is less than air
Liquor Ammonia
Highly concentrated aqueous solution of Ammonia
Liquid Ammonia
Ammonia liquified easily by applying pressure
Uses of Ammonia
For the manufacture of chemical fertilizers
As refrigerant in ice plant
To clean tiles and windows pans
As a laboratory reagent
Reversible reaction
Taking place in both direction
It involves forward and backward reaction
Forward reaction-reactant change in to product
Backward reaction-product change back in to reactant.
Forward Reaction
Eg. NH3+HCI^NH4CI
Backward Reaction
NH4CI^NH3+HCl
Irreversible reaction-Reactant give product only
Eg. NaOH+HCI^NaCI+H2O
Chemical equilibrium: Stage at which the rate of forward reaction become equal to backward reaction.
Characteristics of Chemical equilibrium
Both reactant and product coexist
Rate of forward and backward reaction become equal
Dynamics at molecular level-because forward and backward reaction occur simultaneously at equal rate.
Occur in closed system
Le – Chatelier principle
When the concentration, pressure or temperature of a system at equilibrium is changed, the system will readjust itself so as to nullify the effect of that change and attained a new state of equilibrium.
Influence of concentration in equilibrium
When increase the concentration of reactant or decrease the concentration of product will increase the rate of forward reaction
Increase the concentration of product increase backward reaction.
e N2+ 3 H2^ 2NH3
o To increase rate of forward reaction-increase the concentration of N2 or H2 o To remove ammonia from the system
Effect of pressure–Influence in the case of gases only (Boyls law-. Pressure is inversely proportion to Volume)
e N2 + 3 H2^ 2NH3
4 ; 2
Here total volume of reactant is 4 and that of product is 2
When pressure of system increases volume (number of molecule) decreases on forward direction. Hence forward reaction increases
.
Pressure decreases volume increases (number of molecule increases) on backward direction. Hence backward reaction increases.
2^2
There is no chanqe in total number of molecule of reactant and product. Hence pressure will not have any effect on equilibrium.
Effect of temperature
When temperature increases direction at which endothermic reaction increases, le.,If forward reaction is endothermic when temperature increases forward reaction increases.
Endothermic
CaCOg” CaO + CO2
Exothermic
Here forward reaction is endothermic. When temperature increases forward reaction increases.
Temperature decreases backward reaction increases because it is exothermic.
Sulphuric acid (H2SO4)
Known as king of chemicals
Industrial Preparation
s + o2 so2
2SO2 + O2 ‘VA、2SO3
SO3 + H2SO4 * H2S2O7 (Oleum)
H2S2O7 + H2O—— 2 H2SO4
Chemical Properties
Dehydrating nature
Concentrated H2SO4 absorbs chemically combined water or hydrogen and oxygen from substances in the ratio corresponding to that of water. This process is called dehydration. Sulphuric acid is a strong dehydrating agent. Example:
Conc.H2SO4
Drying nature
Concentrated H2SO4 is used as a drying agent in the preparation of Cl2, SO2, HCI etc. Drying agents are substances capable of absorbing the moisture from a substance. Reaction with Salts
Concentrated sulphuric acid react with chlorides forming hydrogen chloride.
NaCI + H2SO4 NaHSO4 + HCI
Concentrated sulphuric acid react with nitrates forming nitric acid
KNO3 + H2SO4 KHSO4 + HNO3
Oxidising nature
The oxidation state of carbon is increased from 0 to +4. That is, carbon is oxidized.
Oxidation state of sulphur is decreased from +6 to +4. That is, sulphur is reduced. Or sulphuric acid acts as oxidizing agent.
Identification of sulphate ions
Sulphate salts react with barium chloride forming white precipitate of barium sulphate. This precipitate won’t dissolve in dilute hydrochloric acid.
