01
True or false
1 point
True or false: Heat flows spontaneously from a hotter object to a colder object.
Free Practice Quiz Question List
09/14 Thermochemistry Online Quiz Questions
Use this free practice quiz with 20 questions to review 09/14 Thermochemistry, test your knowledge, and prepare for your next test or exam.
20 questions
02
Choose one
1 point
A gas is compressed against an external pressure. Which statement correctly describes the pressure–volume work using the chemistry sign convention?
- A
The system does positive work on the surroundings.
- B
The surroundings do positive work on the system.
- C
The system absorbs negative heat.
- D
The system’s internal energy must decrease.
03
Fill in the blank
1 point
Complete the first-law expression: ΔU =
04
Written response
1 point
What one-word classification describes a process that releases heat to its surroundings?
05
Choose one
1 point
How much heat is absorbed when 50.0 g of water warms from 20.0 °C to 30.0 °C? Use c = 4.184 J g⁻¹ °C⁻¹.
- A
0.2092 kJ
- B
1.046 kJ
- C
2.092 kJ
- D
20.92 kJ
06
True or false
1 point
True or false: For a bomb calorimeter operating at constant volume, the measured heat is related most directly to ΔU rather than ΔH.
- A
True
- B
False
07
Choose all
1 point
A reaction in a coffee-cup calorimeter warms the solution. Select all statements that must be correct when the calorimeter’s heat capacity is negligible.
- A
q_solution is positive.
- B
q_rxn is negative.
- C
The reaction is exothermic.
- D
q_rxn = −q_solution.
08
Fill in the blank
1 point
Using Hess’s law, calculate ΔH for C(s) + O₂(g) → CO₂(g) when C(s) + ½O₂(g) → CO(g) has ΔH = −110.5 kJ and CO(g) + ½O₂(g) → CO₂(g) has ΔH = −283.0 kJ. Enter the result, including its unit:
09
Written response
1 point
A reaction has an enthalpy change of −250 kJ per mole of reaction as written. What is q for 0.400 mol of reaction? Enter the value in kJ, within ±0.01 kJ.
10
Choose all
1 point
Select all statements that correctly describe standard enthalpies of formation.
- A
It forms exactly 1 mol of the compound.
- B
It starts with the constituent elements in their standard states.
- C
It may form any amount of the compound without changing the definition.
- D
An element in its most stable standard state has ΔH_f° = 0.
11
Choose one
1 point
For the reaction A + B → C, ΔH_f°(A) = −50 kJ mol⁻¹, ΔH_f°(B) = −80 kJ mol⁻¹, and ΔH_f°(C) = −200 kJ mol⁻¹. What is ΔH_rxn°?
- A
−330 kJ mol⁻¹
- B
−70 kJ mol⁻¹
- C
+70 kJ mol⁻¹
- D
+330 kJ mol⁻¹
12
True or false
1 point
True or false: According to Hess’s law, the enthalpy change between fixed initial and final states is independent of the pathway.
- A
True
- B
False
13
Choose one
1 point
A thermochemical equation has ΔH = −120 kJ as written. What is ΔH for the reverse reaction with every coefficient divided by 2?
- A
−240 kJ
- B
−60 kJ
- C
+60 kJ
- D
+240 kJ
14
Open ended
1 point
Explain how coffee-cup calorimetry and bomb calorimetry differ in operating conditions and in whether the measured heat is related most directly to ΔH or ΔU. Include the sign relationship between q_rxn and the heat absorbed by the solution in a coffee-cup experiment.
15
Choose one
1 point
A hot metal sample is placed in cooler water in an insulated container. In which direction does heat initially transfer?
- A
The water transfers heat to the metal because water has greater thermal energy.
- B
The metal transfers heat to the water because the metal is hotter.
- C
Neither substance transfers heat because both are in thermal contact.
- D
Heat transfers from the water to the metal because the metal has a higher specific heat.
16
Choose one
1 point
A system absorbs 180 J of heat and does 55 J of work on its surroundings. What is the system’s change in internal energy, ΔU?
- A
−235 J
- B
−125 J
- C
+125 J
- D
+235 J
17
Choose one
1 point
The combustion reaction CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(l) has ΔH = −890.3 kJ. What is ΔH for the reverse reaction, CO₂(g) + 2 H₂O(l) → CH₄(g) + 2 O₂(g), as written?
- A
−1780.6 kJ
- B
−890.3 kJ
- C
+445.15 kJ
- D
+890.3 kJ
18
Written response
1 point
How much heat is absorbed when 50.0 g of water warms from 18.0 °C to 28.0 °C? Use c = 4.184 J g⁻¹ °C⁻¹ and report the result in kJ to the nearest 0.01 kJ. Answers within 0.01 kJ are accepted.
19
Written response
1 point
Two steps are A + B → C with ΔH = −120 kJ and C → D with ΔH = +35 kJ. Using Hess’s law, what is ΔH for the overall reaction A + B → D?
20
Choose one
1 point
For which species is the standard enthalpy of formation defined as zero?
- A
ΔHf°[O(g)]
- B
ΔHf°[O₃(g)]
- C
ΔHf°[O₂(g)]
- D
ΔHf°[H₂O(l)]