Free Practice Quiz Question List

7 Thermochemistry Online Quiz Questions

Use this free practice quiz with 20 questions to review 7 Thermochemistry, test your knowledge, and prepare for your next test or exam.

20 questions

Choose one

1 point

A chemical system absorbs heat from its surroundings. Which statement correctly describes the heat transfer using the chemistry sign convention?

A
The system releases heat, so $q>0$ .
B
The system absorbs heat, so $q>0$ .
C
The system absorbs heat, so $q<0$ .
D
The system does work, so $q>0$ .

True or false

1 point

Two different paths take a system from the same initial state to the same final state. The change in internal energy is the same for both paths.

A
True
B
False

Fill in the blank

1 point

A reaction has $\Delta H<0$ . It is .

Choose one

1 point

A gas is compressed against a constant external pressure. Which statement describes the work sign for the gas system?

A
The gas does work on its surroundings, so $w<0$ .
B
The gas does work on its surroundings, so $w>0$ .
C
Work is done on the gas, so $w>0$ .
D
Work is done on the gas, so $w<0$ .

Fill in the blank

1 point

A coffee-cup calorimeter operates approximately at .

Choose one

1 point

A thermochemical equation is reversed without changing its coefficients. What happens to the enthalpy change for the reaction as written?

A
The sign of $\Delta H$ stays the same.
B
The magnitude of $\Delta H$ becomes zero.
C
The magnitude and sign of $\Delta H$ both stay the same.
D
The sign of $\Delta H$ reverses.

True or false

1 point

A temperature increase of $3.0\ ^\circ\text{C}$ has the same size as a temperature increase of $3.0\ \text{K}$ .

A
True
B
False

Written response

1 point

What method uses the addition of enthalpy changes for multiple steps to determine the enthalpy change for an overall process?

Choose all

1 point

In an insulated coffee-cup calorimetry experiment, a reaction warms the solution. Assume heat exchange with the cup and outside environment is negligible. Select all statements that must be true.

A
The solution gains heat, so $q_{\text{solution}}>0$ .
B
The reaction and solution both have positive heat transfer.
C
$q_{\text{rxn}}=-q_{\text{solution}}$ .
D
The solution's heat gain must be greater in magnitude than the reaction's heat loss.

True or false

1 point

A bomb calorimeter is rigid and operates at constant volume. The reaction heat measured there corresponds to $\Delta U$ , not directly to $\Delta H$ .

A
True
B
False

Written response

1 point

A gas expands by $2.00\ \text{L}$ against a constant external pressure of $1.50\ \text{atm}$ . Using $1\ \text{L·atm}=101.325\ \text{J}$ , calculate the work for the gas system in joules and round to the nearest joule.

Choose all

1 point

When calculating $\Delta H^\circ_{\text{rxn}}$ from standard enthalpies of formation, select all correct procedures.

A
Use the coefficients in the balanced equation to weight each substance's formation enthalpy.
B
Subtract the weighted reactant sum from the weighted product sum.
C
Subtract the weighted product sum from the weighted reactant sum.
D
Use only the formation enthalpy of the product with the largest coefficient.

Open ended

1 point

A reaction warms $40.0\ \text{g}$ of water by $2.50\ ^\circ\text{C}$ in an insulated coffee-cup calorimeter. Assume the solution behaves like water, with $c=4.184\ \text{J g}^{-1}\,^{\circ}\text{C}^{-1}$ , and neglect heat exchange with the cup and outside environment. Calculate the heat gained by the water and the reaction heat. Show the energy balance and signs.

Choose one

1 point

Under which condition does heat transferred to a system equal its enthalpy change?

A
At constant volume, for any type of work
B
At constant pressure, when the only work is pressure–volume work
C
Only when the system exchanges no heat
D
Whenever the system's temperature is constant

Choose one

1 point

A reaction has $\Delta H>0$ . What does this tell you about the reaction?

A
The system releases heat, so the process is exothermic
B
The system absorbs heat, so the process is endothermic
C
The surroundings must do positive work on the system
D
The system's internal energy must decrease

Choose one

1 point

A system absorbs $240\ \text{J}$ of heat while doing $95\ \text{J}$ of work on its surroundings. What is $\Delta U$ ?

A
$-335\ \text{J}$
B
$145\ \text{J}$
C
$240\ \text{J}$
D
$335\ \text{J}$

Written response

1 point

What principle explains why enthalpy changes for individual reaction steps add to the enthalpy change for the overall process?

Choose one

1 point

A rigid bomb calorimeter operates at constant volume. What thermodynamic quantity does its measured reaction heat correspond to?

A
It measures $\Delta H$ directly because it operates at constant pressure
B
It measures the heat capacity of the reaction products
C
Its reaction heat corresponds to $\Delta U$ because it operates at constant volume
D
It measures only the heat absorbed by the surroundings

Choose one

1 point

A thermochemical equation has $\Delta H=-120\ \text{kJ}$ for the reaction as written. If only one third of that amount of reaction occurs, what is $\Delta H$ for the amount that occurs?

A
$-360\ \text{kJ}$
B
$-40\ \text{kJ}$
C
$40\ \text{kJ}$
D
$-120\ \text{kJ}$

Written response

1 point

In an insulated coffee-cup calorimeter, $25.0\ \text{g}$ of water warms by $4.00\ ^\circ\text{C}$ . Assume the solution behaves like water, with $c=4.184\ \text{J g}^{-1}\,^{\circ}\text{C}^{-1}$ , and neglect heat exchange with the cup and outside. What is the reaction heat in joules?