What is the mass of sodium thiosulphate pentahydrate required to prepare 250cm3 of a 0.14mol/dm3 solution
2 answers:
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Answer :
(A) ΔH is positive and ΔS is negative → (2) Spontaneous in reverse at all temperatures
(B) ΔH is positive and ΔS is positive → (3) Spontaneous as written above a certain temperature
(C) ΔH is negative and ΔS is positive → (1) Spontaneous as written at all temperatures
(D) ΔH negative and ΔS is negative → (4) Spontaneous as written below a certain temperature
Explanation :
According to Gibb's equation:
= Gibbs free energy
= enthalpy change
= entropy change
T = temperature in Kelvin
As we know that:
= +ve, reaction is non spontaneous
= -ve, reaction is spontaneous
= 0, reaction is in equilibrium
(A) ΔH is positive and ΔS is negative.
The reaction is non-spontaneous at all temperatures or spontaneous in reverse at all temperatures.
(B) ΔH is positive and ΔS is positive.
(at low temperature) (non-spontaneous)
(at high temperature) (spontaneous)
The reaction is spontaneous as written above a certain temperature.
(C) ΔH is negative and ΔS is positive.
The reaction is spontaneous as written at all temperatures
(D) ΔH is negative and ΔS is negative.
(at high temperature) (non-spontaneous)
(at low temperature) (spontaneous)
The reaction is spontaneous as written below a certain temperature.