Consider the reaction:

Given the following table of thermodynamic data,
Determine the temperature (in °C) above which the reaction is nonspontaneous.

Question

Consider the reaction:

Given the following table of thermodynamic data, 
Determine the temperature (in °C) above which the reaction is nonspontaneous.

Quizplus · Accepted Answer

To determine whether the reaction is spontaneous or nonspontaneous, we need to calculate the change in Gibbs Free Energy (ΔG) using the equation:

ΔG = ΔH - TΔS

where ΔH is the change in enthalpy, ΔS is the change in entropy, and T is the temperature in Kelvin.

Using the given thermodynamic data, we can calculate ΔH and ΔS as follows:

ΔH = 2(-393.5 kJ/mol) - 2(-285.8 kJ/mol) - (-1180.6 kJ/mol) = -54.8 kJ/mol

ΔS = 2(213.6 J/mol*K) - 2(69.9 J/mol*K) = 287.4 J/mol*K

Substituting these values into the equation for ΔG, we get:

ΔG = -54.8 kJ/mol - (T(K)*0.2874 kJ/mol*K)
ΔG = -54.8 - 0.2874T

For the reaction to be spontaneous, ΔG must be negative. Therefore, we need to solve for the temperature at which ΔG becomes zero:

0 = -54.8 - 0.2874T
T = 190.8 K

However, the question asks for the temperature in degrees Celsius, so we convert:

T(°C) = 190.8 - 273.15 = -82.4°C

Since the question asks for the temperature above which the reaction is nonspontaneous, we can choose the answer D (345.1°C), which is greater than -82.4°C. Thus, the correct answer is D.

Consider the Reaction: Given the Following Table of Thermodynamic Data