NEET Thermodynamics — Set 14

Question 1

The standard enthalpy of formation of $CO_2(g)$ is -393.5 kJ/mol. This value refers to the formation of:

Accepted Answer

The standard enthalpy of formation is the enthalpy change when 1 mol of a compound is formed from its elements in their standard states, i.e., $C(s) + O_2(g) \rightarrow CO_2(g)$.

Question 2

Calculate $\Delta G^\circ$ for a reaction with $K = 2 \times 10^6$ at 298 K. ($R = 8.314 \, \text{J/mol·K}$)

Accepted Answer

$\Delta G^\circ = -RT \ln K = -8.314 \times 298 \times \ln(2 \times 10^6) = -2477.6 \times 14.509 = -35962 \, \text{J/mol} = -35.96 \, \text{kJ/mol}$.

Question 3

For a reaction at constant volume, the heat absorbed is equal to:

Accepted Answer

At constant volume, $w = -p\Delta V = 0$, so from the first law, $\Delta U = q_v$, the heat absorbed at constant volume.

NEET Chemistry: Thermodynamics — Practice Set 14

Q1. The standard enthalpy of formation of \(CO_2(g)\) is -393.5 kJ/mol. This value refers to the formation of:

Q2. Calculate \(\Delta G^\circ\) for a reaction with \(K = 2 \times 10^6\) at 298 K. (\(R = 8.314 \, \text{J/mol·K}\))

Q3. For a reaction at constant volume, the heat absorbed is equal to:

Q4. For \( C_2H_4(g) + H_2(g) \rightarrow C_2H_6(g) \), \( \Delta H = -137.00 \, \text{kJ/mol} \) at 298 K. What is \( \Delta U \)? (\( R = 8.314 \, \text{J/mol·K} \))

Q5. For an ideal gas undergoing an isochoric process, which of the following is always zero?

Q7. A system absorbs 600 J of heat at constant volume, and its internal energy increases by 600 J. What is the work done?

Q8. For a reaction with \(\Delta H = -50 \, \text{kJ/mol}\) and \(\Delta S = -100 \, \text{J/K}\), at what temperature does \(\Delta G = 0\)?

Q9. The heat capacity of a gas at constant volume is 20 J/mol·K. What is \(C_p\) if it is an ideal gas? (\(R = 8.314 \, \text{J/mol·K}\))

Q10. For \( CO(g) + H_2O(g) \rightarrow CO_2(g) + H_2(g) \), \( \Delta H = -41.20 \, \text{kJ/mol} \) at 298 K, what is \( \Delta U \)? (\( R = 8.314 \, \text{J/mol·K} \))