What is the value for [tex]$\Delta G$[/tex] at 5000 K if [tex]$\Delta H=-220 \, \text{kJ/mol}$[/tex] and [tex]$\Delta S=-0.05 \, \text{kJ/(mol \cdot K)}$[/tex]?

A. 470 kJ
B. 30 kJ
C. -195 kJ
D. -470 kJ



Answer :

To determine the Gibbs free energy change [tex]\(\Delta G\)[/tex] at a temperature of 5000 K, given the change in enthalpy [tex]\(\Delta H = -220 \text{ kJ/mol}\)[/tex] and the change in entropy [tex]\(\Delta S = -0.05 \text{ kJ/(mol⋅K)}\)[/tex], we use the fundamental thermodynamic relation:

[tex]\[ \Delta G = \Delta H - T \Delta S \][/tex]

Here's the step-by-step process to solve this:

1. Identify the given values:
- Temperature [tex]\(T = 5000 \text{ K}\)[/tex]
- Change in enthalpy [tex]\(\Delta H = -220 \text{ kJ/mol}\)[/tex]
- Change in entropy [tex]\(\Delta S = -0.05 \text{ kJ/(mol⋅K)}\)[/tex]

2. Substitute the given values into the equation:

[tex]\[ \Delta G = \Delta H - T \Delta S \][/tex]

Substituting the given values:

[tex]\[ \Delta G = -220 \text{ kJ/mol} - (5000 \text{ K} \times -0.05 \text{ kJ/(mol⋅K)}) \][/tex]

3. Perform the multiplication inside the parenthesis:

[tex]\[ 5000 \text{ K} \times -0.05 \text{ kJ/(mol⋅K)} = -250 \text{ kJ/mol} \][/tex]

4. Subtract this value from [tex]\(\Delta H\)[/tex]:

[tex]\[ \Delta G = -220 \text{ kJ/mol} - (-250 \text{ kJ/mol}) \][/tex]

Simplifying the subtraction:

[tex]\[ \Delta G = -220 \text{ kJ/mol} + 250 \text{ kJ/mol} \][/tex]

5. Add the values:

[tex]\[ \Delta G = 30 \text{ kJ/mol} \][/tex]

So, the value for [tex]\(\Delta G\)[/tex] at 5000 K is:

[tex]\(\boxed{30 \text{ kJ}}\)[/tex]

Hence, the correct answer is:

B. 30 kJ