Chemical Thermodynamics

In thermodynamics, a system is classified as heterogeneous if it consists of two or more distinct phases. Which of the following examples represents a heterogeneous system?

A system is considered macroscopic if it contains:

The portion of the universe that can interact with the system is called the:

Which system allows for the exchange of heat but has a fixed mass?

In the diagram below, Subsystem A and Subsystem B are separated by a fixed copper plate that allows heat transfer but prevents the mixing of chemicals. The entire assembly (A + B) is enclosed by a vacuum-jacketed, rigid outer wall. Identify the correct thermodynamic classification for Subsystem A alone and for the total combined system (A + B).

A laboratory autoclave is used to sterilize glassware. During the 'Heating Phase' (State 1), the exhaust valve is tightly shut while heat is supplied to generate steam. During the 'Pressure-Release Phase' (State 2), the valve is opened to allow steam to escape into the atmosphere. Based on the provided diagram, identify the transition in the thermodynamic classification of the system inside the autoclave.

A sealed bulb containing a mixture of $NO_2$ and $N_2O_4$ gases is an example of which type of system?

Which of the following is true for an 'Isolated System'?

A system consists of a block of ice at $273 K$ melting into water. If this happens in a perfectly insulated container of fixed volume, the system is:

In a thermos flask, which part specifically minimizes energy transfer by radiation?

The universe is defined in thermodynamics as:

In a reversible process, the system and surroundings can be restored to their original states. This process is usually:

A well-insulated container preventing heat flow to surroundings defines which process?

The change in internal energy ($\\Delta U$) for an adiabatic process is equal to:

A thermodynamic system is taken through a cyclic process $1 \rightarrow 2 \rightarrow 3 \rightarrow 1$ as shown in the diagram.

• In process $1 \rightarrow 2$, the system absorbs $60\text{ J}$ of heat and performs $25\text{ J}$ of work on the surroundings.
• In process $2 \rightarrow 3$, the system releases $45\text{ J}$ of heat at constant volume.
• In process $3 \rightarrow 1$, the surroundings perform $20\text{ J}$ of work on the system. Based on the First Law of Thermodynamics, what is the heat exchange ($q$) for the process $3 \rightarrow 1$?

In an isothermal expansion of an ideal gas against a vacuum (free expansion), which of the following is true?

If a system is perfectly insulated from its surroundings, which thermodynamic quantity must be zero for any process it undergoes?

A system is taken from state A to state B along path ACB and returns to A along path BDA. If $q_{ACB} = 50\text{ J}$ and $w_{ACB} = -20\text{ J}$, and $w_{BDA} = +15\text{ J}$, what is $q_{BDA}$?

Calculate the difference between molar heat capacity at constant pressure and constant volume for an ideal gas.

During the isothermal expansion of an ideal gas into a vacuum, which of the following is non-zero?

Which property of a system is referred to as 'heat content'?

The energy required to completely separate one mole of a solid ionic compound into gaseous constituent ions is called:

Which of the following is true for an isolated system?

Enthalpy change at constant pressure is denoted by:

In the thermochemical cycle shown below, $\Delta H_1$ represents the lattice enthalpy of an ionic compound $MX(s)$, $\Delta H_2$ represents the enthalpy of hydration of the gaseous ions, and $\Delta H_3$ represents the enthalpy of solution. Which of the following expressions correctly relates these enthalpy changes according to Hess's Law?

The standard enthalpy of formation is measured under which set of conditions?

For the reaction $CO(g) + \frac{1}{2}O_2(g) \rightarrow CO_2(g)$, the value of $\Delta n_g$ is:

Identify which property is being described: It is the enthalpy change when one mole of an ionic compound is formed from its gaseous ions.

Calculate the enthalpy of hydrogenation of 1,3-butadiene ($C_4H_6$) to butane ($C_4H_{10}$) if the enthalpies of combustion of $C_4H_6$, $C_4H_{10}$, and $H_2$ are $-2540$, $-2878$, and $-286\ kJ/mol$ respectively.

The $Δ H$ for $A \rightarrow B$ is $10\ kJ/mol$. If the activation energy for the forward reaction is $50\ kJ/mol$, what is the activation energy for the backward reaction?

When summing equations for Hess's Law, if a substance appears on both the reactant and product sides of the overall resulting equation, it can be:

Is Hess's Law valid for both endothermic and exothermic reactions?

Hess's Law is also known as the Law of Constant ___ Summation.

If a process involves the conversion of $A$ to $D$ via $A \rightarrow B$, $B \rightarrow C$, and $C \rightarrow D$, and the enthalpies are $h_1, h_2, h_3$, the enthalpy for $A \rightarrow D$ is:

Calculate the enthalpy change for the reaction $2S(s) + 3O_2(g) \rightarrow 2SO_3(g)$ given:

1. $S(s) + O_2(g) \rightarrow SO_2(g); \Delta H = -297\text{ kJ}$
2. $2SO_2(g) + O_2(g) \rightarrow 2SO_3(g); \Delta H = -198\text{ kJ}$

The heat of reaction for $A + B \rightarrow C$ is $-50\text{ kJ}$. For $D + E \rightarrow C$, it is $-80\text{ kJ}$. What is the heat of reaction for $A + B \rightarrow D + E$?

Calculate $\Delta H$ for $2C(s) + H_2(g) \rightarrow C_2H_2(g)$ using:

1. $C_2H_2(g) + \frac{5}{2}O_2(g) \rightarrow 2CO_2(g) + H_2O(l); \Delta H = -1299\text{ kJ}$
2. $C(s) + O_2(g) \rightarrow CO_2(g); \Delta H = -393.5\text{ kJ}$
3. $H_2(g) + \frac{1}{2}O_2(g) \rightarrow H_2O(l); \Delta H = -285.8\text{ kJ}$

Find the standard enthalpy of formation of $SO_3(g)$ given: $S(s) + O_2(g) \rightarrow SO_2(g)$ ; $\Delta H = -296.8\text{ kJ/mol}$ $SO_2(g) + 0.5O_2(g) \rightarrow SO_3(g)$ ; $\Delta H = -98.9\text{ kJ/mol}$

The enthalpy of hydrogenation of cyclohexene to cyclohexane is $-119.6\text{ kJ/mol}$. If the theoretical enthalpy of hydrogenation of benzene to cyclohexane (assuming three isolated double bonds) is $-358.8\text{ kJ/mol}$, but the experimental value is $-208.1\text{ kJ/mol}$, what is the resonance energy of benzene?

Calculate the enthalpy of atomization of benzene ($C_6H_6, g$) given the bond enthalpies: $C-H = 414\text{ kJ/mol}$ and the hybrid bond enthalpy in the ring is estimated at $506\text{ kJ/mol}$ per $C-C$ bond equivalent.

The enthalpy of atomization for $Na(s)$ is the energy required to convert it into:

Which of the following is correct for the process of condensation?

When a salt is dissolved in water, if the lattice enthalpy is much higher than the hydration enthalpy, the salt is likely to be:

The term used for the enthalpy change when one mole of a substance is completely burnt in excess of oxygen is:

Calculate the enthalpy change for the reaction: $C(graphite) + \frac{1}{2}O_{2}(g) \rightarrow CO(g)$, given $\Delta_{c}H(graphite) = -393.5\ kJ\ mol^{-1}$ and $\Delta_{c}H(CO) = -283.0\ kJ\ mol^{-1}$.

For a reaction $X_{2}(g) \rightarrow 2X(g)$, if the enthalpy change is $+242\ kJ\ mol^{-1}$, the bond enthalpy of $X-X$ is:

The enthalpy of formation of $H_{2}O(l)$ is $-285.8\ kJ\ mol^{-1}$. What is the enthalpy of formation of $H_{2}O(g)$ if the enthalpy of vaporization is $44.0\ kJ\ mol^{-1}$?

The heat of formation of $C_{2}H_{5}OH(l)$ is $-277\ kJ/mol$. Its heat of combustion is $-1367\ kJ/mol$. Calculate the heat of formation of $CO_{2}(g)$ and $H_{2}O(l)$ in a $2:3$ ratio, given that their individual values satisfy the combustion equation.

Calculate the average $S-F$ bond energy in $SF_{6}$ if the enthalpy of formation of $SF_{6}(g)$, $S(g)$, and $F(g)$ are $-1100, 275,$ and $80\ kJ/mol$ respectively.

Based on the enthalpy diagram for the different states of $H_{2}O$, which segment represents the enthalpy of sublimation?

For the reaction $2Cl(g) \\rightarrow Cl_2(g)$, the sign of $\\Delta S$ is:

If a process is reversible, the total entropy change of the universe is:

Which of the following indicates that a system has reached maximum disorder?

A reaction with a very large negative $\\Delta G$ value is:

For a reaction $2A(g) + B(g) \rightarrow 2C(g)$, if the reaction is exothermic, it is most likely to be spontaneous at:

The entropy of the universe during a spontaneous adiabatic process:

What is the sign of the entropy change of the surroundings for an endothermic reaction?

For a reaction with $\Delta H > 0$, the spontaneity is driven by:

In the Gibbs Free Energy equation, if $\Delta H$ and $T\Delta S$ are both positive and $\Delta H > T\Delta S$, the reaction is:

A reaction has a negative $\Delta H$ and a negative $\Delta S$. Which of the following is true?

Which of the following would have the least entropy at room temperature?

The entropy change for the surroundings is given by $\Delta S_{surr} = -\Delta H / T$. For an endothermic reaction, $\Delta S_{surr}$ will be:

If a process is non-spontaneous, what must be true about the $\Delta S_{total}$?

In which case is the entropy change ($\Delta S$) expected to be the smallest (close to zero)?

At what temperature will the reaction $A \rightarrow B$ be at equilibrium if $\Delta H = 30 \, kJ \, mol^{-1}$ and $\Delta S = 60 \, J \, K^{-1} \, mol^{-1}$?

Which of the following will result in a decrease in entropy?

Trouton's rule states that the entropy of vaporization for many liquids at their boiling point is approximately:

The statistical definition of entropy was given by:

For a reversible cyclic process, the net change in the entropy of the system is:

Which of the following processes involves the greatest increase in entropy?

A reaction has $\Delta G^∘ < 0$. Which of the following is true about its spontaneity?

In the expression $\Delta G = \Delta H - T\Delta S$, if the units of $\Delta H$ are $kJ/mol$ and $\Delta S$ are $J/K \cdot mol$, what must be done to calculate $\Delta G$ correctly?

If we double the coefficients in a balanced chemical equation, what happens to the value of $\Delta G^∘$?

If $\Delta G$ is zero for a phase change (like melting), it means the system is at its:

If the ratio of $Q/K$ is less than 1, what is the sign of $\Delta G$ and what is the direction of the reaction?

The value of $\Delta G$ for a system is related to the 'useful' work ($w_{non-PV}$) by:

When $\Delta G^\circ$ is calculated using the equation $\Delta G^\circ = \sum \Delta_f G^\circ_{products} - \sum \Delta_f G^\circ_{reactants}$, the value refers to:

Which of the following conditions ensures that a reaction is at equilibrium?

For a reaction where $\Delta n_g = 0$, what is the relationship between $\Delta G^\circ$ based on $K_p$ and $\Delta G^\circ$ based on $K_c$?

If the equilibrium constant for a reaction is $K = 1.0 \times 10^{-5}$, which statement is most accurate regarding the reaction's Gibbs energy?

The temperature change in a calorimeter is $5 \, K$. If the total heat capacity of the calorimeter and water is $500 \, J/K$, the heat of reaction is:

Which of these factors does NOT affect the specific heat capacity of a substance?

In the equation $q = m \cdot c \cdot \Delta T$, if $m$ is in grams and $c$ is in $J \, g^{-1} \, K^{-1}$, the unit of $q$ is:

To find the heat of a reaction in a calorimeter, we must account for:

For the reaction $H_2(g) + 0.5 O_2(g) \rightarrow H_2O(l)$, the value of $\Delta H - \Delta U$ is equal to:

If we double the mass of a substance, its specific heat capacity will:

Heat of combustion is always:

For the combustion of benzoic acid in a bomb calorimeter, if the oxygen is not in excess, the measured $\Delta U$ will be:

If a reaction $A + B \rightarrow C$ is exothermic, how will the temperature of the water in a coffee-cup calorimeter change?

A bomb calorimeter experiment uses 1000 g of water. If the bomb itself is made of 500 g of steel ($c_{s} = 0.45\ J/g\cdot K$), what percentage of the total heat capacity is contributed by the bomb vessel itself?