You visited us 1 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Standard XII

Chemistry

Spontaneity

The molar hea...

Question

The molar heat capacities at constant pressure for $A, B$ and $C$ are $3, 1.5$ and $2$ J/K mol. The enthalpy of reaction and entropy of reaction, $A + 2 B \to 3 C$ are $20$ kJ/mol and $20$ J/K mol at $300 K$ .

Calculate $Δ G$ (in kJ/mol) for the reaction,
$\frac{1}{2} A + B \to \frac{3}{2} C$

Open in App

Solution

For the reaction $A + 2 B \to 3 C$

$Δ G = Δ H - T Δ S$

$= 20000 J m o l^{- 1} - 300 K \times 20 J m o l^{- 1} K^{- 1}$

$= 14000 J m o l^{- 1} = 14 k J m o l^{- 1}$

For the reaction $\frac{1}{2} A + B \to \frac{3}{2} C$ ,

$Δ G = \frac{14 k J m o l^{- 1}}{2} = 7 k J m o l^{- 1}$ .

Hence, $Δ G$ for the reaction is $7 k J m o l^{- 1}$ .

Suggest Corrections

Similar questions

Q. The molar heat capacities at constant pressure (assume constant with respect to temperature) of

A, B

and

C

are in the ration of

1.5 : 3.0 : 2.0

If enthalpy change for the exothermic reaction

A + 2 B \to 3 C

300 K

- 10 k J / m o l

C_{p, m} (B)

300 J / m o l

then enthalpy change at

310 K

is:

Q. For the reaction

2 N O (g) + O_{2} (g) ⟶ 2 N O_{2} (g)

Calculate

Δ G

700 K

when enthalpy and entropy changes are

- 113 k J {m o l}^{- 1}

and

- 145 J K^{- 1} {m o l}^{- 1}

respectively.

Q. The equilibrium constant for the reaction given below is

2.0 \times 10^{- 7}

at 300 K. Calculate the standard free energy change for the reaction.

P C l_{5} (g) ⇌ P C l_{3} (g) + C l_{2} (g)

Also, calculate the standard entropy change if,

Δ H^{\circ} = 28.40 k J m o l^{- 1}

For a reaction at $25^{\circ} C$ enthalpy change ( $△ H$ ) and entropy change ( $△ S$ ) are -11.7 K J $m o l^{- 1}$ and -105 J $m o l^{- 1}$ $K^{- 1}$ , respectively. It is a spontaneous reaction

Standard enthalpy and standard entropy for the oxidation of $N H_{3}$ at $298$ K are $- 382.64$ $kJ {mol}^{- 1}$ and $- 145.6$ $J {mol}^{- 1} K^{- 1}$ respectively. Standard free energy change (in ${kJ mol}^{- 1}$ ) for the same reaction at $298$ K is:

Join BYJU'S Learning Program

The molar heat capacities at constant pressure for A,B and C are 3, 1.5 and 2 J/K mol. The enthalpy of reaction and entropy of reaction, A+2B→3C are 20kJ/mol and 20J/K mol at 300K. Calculate ΔG (in kJ/mol) for the reaction,12A+B→32C

For the reaction A+2B→3CΔG=ΔH−TΔS=20000J mol−1−300K×20J mol−1 K−1=14000J mol−1=14 kJ mol−1For the reaction 12A+B→32C,ΔG=14kJ mol−12=7 kJ mol−1.Hence, ΔG for the reaction is 7 kJ mol−1.

The molar heat capacities at constant pressure for $A, B$ and $C$ are $3, 1.5$ and $2$ J/K mol. The enthalpy of reaction and entropy of reaction, $A + 2 B \to 3 C$ are $20$ kJ/mol and $20$ J/K mol at $300 K$ .

Calculate $Δ G$ (in kJ/mol) for the reaction,
$\frac{1}{2} A + B \to \frac{3}{2} C$