An endothermic reaction A → B proceeds to completion. Predict the sign of ∆ S .

For endothermic reaction, ∆ H is positive. So an endothermic reaction can proceed by decreasing its Gibbs energy, if ∆ H - T ∆ S is negative, which is possible only if ∆ S is positive. Hence, the sign of the entropy change is positive and the reaction is feasible.

An endothermic reaction A → B proceeds to completion. Predict the sign of ∆ S .

For endothermic reaction, ∆ H is positive. So an endothermic reaction can proceed by decreasing its Gibbs energy, if ∆ H - T ∆ S is negative, which is possible only if ∆ S is positive. Hence, the sign of the entropy change is positive and the reaction is feasible.

What will be the sign of ∆ S for the reaction: N 2 ( g ) + O 2 ( g ) → 2 NO ( g ) ? Give reasons in support of your answer.

The reaction of nitrogen and oxygen is given as follows, N 2 ( g ) + O 2 ( g ) → 2 NO ( g ) . There are two moles of different reactants involved in this reaction and there are two moles of only one product. Therefore, the sign of entropy change is zero, ∆ S = 0 . There are two moles of two different gaseous reactants which have similar randomness as two moles of the gaseous product. Hence, the randomness remains same.

E M B I B E

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 55

HARD

11th CBSE

IMPORTANT

Earn 100

An endothermic reaction $A \to B$ proceeds to completion. Predict the sign of $∆ S$ .

Important Questions on Thermodynamics

EASY

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 55

What will be the sign of

∆ S

for the reaction:

N_{2} (g) + O_{2} (g) \to 2 NO (g)

? Give reasons in support of your answer.

MEDIUM

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 56

Predict the enthalpy change, free energy change and entropy change when ammonium chloride is dissolved in water and the solution becomes colder.

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 57

For a hypothetical process, $A \to B$ , predict whether the process is spontaneous or not when $ΔH = + ve$ , $TΔS = - ve$ and $TΔS = ΔH$ .

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 57

For a hypothetical process, $A \to B$ , predict whether the process is spontaneous or not when $ΔH = - ve$ , $TΔS = - ve$ and $TΔS > ΔH$ .

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 57

For a hypothetical process, $A \to B$ , predict whether the process is spontaneous or not when $ΔH = - ve, TΔS = - ve$ and $ΔH > TΔS$ .

MEDIUM

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 57

Total number of

σ -

bonds present in the molecule of propyne is

MEDIUM

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 58

Starting with the thermodynamic relationships,

G = H - TS

, derive the following relationship:

ΔG = - {TΔS}_{total} .

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>ADDITIONAL QUESTIONS>Q 59

Write Gibb’s Helmholtz equation which relates the enthalpy change and the energy change of a process at constant temperature and pressure. Explain the effect of temperature on feasibility for endothermic process in terms of Gibb’s Helmholtz equation.