A reaction has ÄH = -378 kJ and ÄS = -37 J/K. Calculate ÄG at 25°C to confirm that the reaction is spontaneous.
in kJ
dGo = dH - TdS
dGo = -378 - 298(0.037) = ?
To calculate the change in Gibbs free energy (ΔG) at a given temperature, you can use the equation:
ΔG = ΔH - TΔS
Where:
ΔH is the change in enthalpy
ΔS is the change in entropy
T is the temperature in Kelvin
First, let's convert the given values to proper units:
ΔH = -378 kJ (already in kJ)
ΔS = -37 J/K (convert to kJ/K)
T = 25°C = 298 K
To convert J into kJ, divide by 1000:
ΔS = -37 J/K ÷ 1000 = -0.037 kJ/K
Now, substitute the values into the formula:
ΔG = -378 kJ - (298 K)(-0.037 kJ/K)
ΔG = -378 kJ + 11.026 kJ
ΔG = -366.974 kJ
Therefore, the change in Gibbs free energy (ΔG) at 25°C is approximately -367 kJ.
Since ΔG is negative, the reaction is spontaneous at this temperature.