Long Answer Type(i) Write the equation which relates the number of phases, components and degree of freedom of a system in equilibrium.
(ii) How many phases and components are there in a system consisting of:
(1) a mixture of O2 and N2 gases
(2) N2 gas containing H2O vapour
(3) a mixture of ice and water
(4) a mixture of powdered iron and sulphur
(5) a lump of solid iron (II) sulphide
Give a suitable explanation, in brief, for your answer.
(i) The Gibb’s phase rule equation given below related the number of phases, components
and the degree of freedom of a system in equilibrium.
F = C – P + 2
where F = Number of degrees of freedom,
C = Number of components,
P = Number of phases, and
= represents the temperature and pressure.
(ii) (1) Phases—one (gaseous), Components—two.
(2) Phases—one (gaseous), Components—two.
(3) Phases—two (solid and liquid), Components—one
(4) Phases—one (solid), Components—two
(5) Phases—one (solid), Components—one
Consider the reaction,
A + B → C + D
The initial rates for different initial concentrations of the reactants are given below :
Initial concentration (mol 1– 1Initial rate (mol 1 –1 s– 1)
|
A |
B |
||
|
(i) |
1.0 |
1.0 |
2.0 x 10 – 3 |
|
(ii) |
2.0 |
1.0 |
4.0 x 10– 3 |
|
(iii) |
4.0 |
1.0 |
8.0 x 10– 3 |
|
(iv) |
1.0 |
2.0 |
2.0 x 10– 3 |
|
(v) |
1.0 |
4.0 |
2.0 x 10’3 |
(a) What are the orders with respect to A and B ?
(b) What is the overall order ?
(c) Write the rate law equation.
(d) Calculate the rate constant.
(e) Suggest a possible mechanism.
Explain the principle involved in the following observations :
(i) Cu2+ is precipitated as CuS in the acidic medium while Ni2+ is precipitated as NiS in a basic medium with H2S.
(ii) A solution of a weak acid and its salt with strong base has a definite pH value which does not change appreciably on dilution.
(iii) A solution of sodium chloride is neutral while that of ferric chloride is acidic in nature.
(i) Why could fluorine not be prepared for a long time from HF and metal fluorides either by electrolysis or by any chemical reaction ?
(ii) Describe the modern method for the preparation of fluorine by giving :
(a) Materials used in the construction of the cell.
(b) Electrolyte used.
(c) Electrode reactions.
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