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Physical and Inorganic Chemistry
Chemical equilibrium
What is meant by chemical equilibrium?
Chemical equilibrium is
a state in which the rate of the forward reaction equal of the rate of the
backward reaction.
Types of Chemical Equilibrium
There are two types of chemical equilibrium
i.
Homogeneous
equilibrium: In an equilibrium all
reactants and all products are present in the same phase. It is called
homogeneous equilibrium.
Example: H2(g)+I2(g)⇋2HI(g)
ii.
Heterogeneous
equilibrium: In an equilibrium, the
reactants and the products are present two and more than two phases. It is
called a heterogeneous equilibrium.
Example: CaCO3(s)⇋CaO(s)+CO2(g)
Why
is equilibrium considered to be a dynamic state?
Both the forward and reverse
reactions are constantly taking place, but their rates are equal, so no net
change occurs in the concentrations of the products and reactants.
What’s reversible
reaction?
A reversible reaction
is one in which the conversion of reactants to products and conversion of products
to reactants occur at the same time.
Example: H2(g)+I2(g)⇋2HI(g)
Le Châtelier’s principle?
If a system
at equilibrium is subjected to a change of pressure, temperature, or number of
moles of a component, there will be a tendency for a net reaction in the
direction that reduces the effect of this change.
Definition and application of equilibrium
constant?
Definition: At
a particular temperature the rate constants are constant. The ratio of the rate
constant of forward reaction to the rate constant of backward reaction should
be a constant is called an equilibrium constant.
Application:
Ø Equilibrium
constant for predicting the extent of reaction.
Ø Equilibrium
constant for predicting the direction of reaction.
Ø Calculating
the equilibrium concentration.
Equilibrium position?
Equilibrium position is the point in a chemical
reaction. At this point, the concentration of the reactant and the
concentration of the products, don’t change.
Themo chemistry
What is thermochemical
reaction? Type of thermochemical reaction?
The balanced chemical
reaction indicates the physical state of the reactants and products and also
indicates heat change known as thermochemical reaction.
Two types of thermochemical reaction
·
Endothermic: When heat is absorbed by the reaction is called
endothermic reaction. (-)
·
Exothermic: When heat is evolved by the reaction is called
exothermic reaction. (+)
What’s spontaneous and
non-spontaneous reaction and examples?
Spontaneous reaction: A spontaneous reaction is one that occurs on its own
without any energy input from outside.
Example: Water flow
will downhill, Ice will melt into water.
Non- spontaneous
reaction: A non- spontaneous
process does not occur on its own. Energy must be added in order for one to
occur.
Example: Pumping of water uphill, Melting ice into water and
boiling water into steam.
What is Hess’s law
The enthalpy change in
a chemical or physical process is the same whether the process is carried out
in a step or in several step.
Glass calorimeter?
An ordinary glass
calorimeter is use to find the value of H for various purpose. It consists of
·
Thermometer.
·
Insulated
container.
·
Stirrer.
Working
·
Reactants are
placed in the calorimeter.
·
When the
reaction proceeds, the heat evolved or absorbed will either warm or cool in the
system.
·
The temperature
of the system is recorded before and after the chemical reaction.
·
Knowing the
change in temperature, mass of reactants and specific heat of the reaction.
What is enthalpy of
combustion?
The enthalpy of
combustion of a substance is defined as the heat energy given out when one mole
of a substance burns completely in oxygen.
What is calcination and smelting process
Calcination: When carbonate ore is
heated for a long time in absence of air it is converted into metal oxide.
Smelting: Smelting process by which a
metal is obtained, either as the element or as a simple compound from its ores
by heating beyond the melting point. Ordinarily in the presence of oxidizing
agents such as air or reducing agents such as coke.
Colloidal
Dispersion
What is Tyndall effect? Example?
The Tyndall effect is an effect of light scattering
in colloidal dispersion, while showing no light in a true solution. This effect
is used to determine whether a mixture is a true solution or colloid.
Example: Light
being shined through water and milk. The light is not reflected when passing
through the water because it is not colloid. It is however reflected when
passes through the milk which is colloidal.
What is Brownian movement? Reason and
example?
Brownian movement: Brownian
movement is the random movement of particles in a liquid due to high
collisions.
Reason: Unequal
and non-uniform bombardment of particles is the reason of Brownian movement.
Example:
· Pollen
grain in oil drop move.
· Plasma
particles in the cell.
Differentiate
between true solution, colloidal solution and suspension?
|
True solution |
Colloidal solution |
Suspension |
|
Homogenous mixture. |
Heterogenous mixture. |
Heterogeneous mixture. |
|
It is transparent |
It is transparent |
It is opaque |
|
Particle size: very small can’t be seen by naked eye. |
Particle size- between true solution and suspension, cannot be
seen by naked eye |
Particle size- small cannot be seen by naked eye |
|
Solute particles don’t settle down when left un-distribute |
Solute particles don’t settle down when left un-distribute |
solute particles settle down when left un-distribute |
|
Filtrations separation – not possible. |
Filtrations separation – not possible |
Filtrations separation – possible |
What is
lyophilic and lyophobic solution with example?
Lyophilic
solution: These are
the colloidal solution in which dispersed particles have strong affinity for
dispersion medium. These solutions are stable and reversible.
Example: Gum, gelatin solution.
Lyophobic
solution: There the
dispersed phase has no affinity for dispersion medium. These solutions are
unstable and are irreversible.
Example: metal in water, metal sulphides.
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