Enthalpy Change - Questions
The Enthalpy Change Concept Builder is comprised of 42 questions. The questions are divided into 18 different Question Groups and spread across three Difficulty Levels. Questions in the same group are rather similar to one another. The Concept Builder is coded to select at random a question from each group until a student is successful with that group of questions.
There are three difficulty levels in the Concept Builder. Those three difficulty levels are differentiated as follows:
- Apprentice Difficulty Level: Question Groups 1-6 ... Identify the correct electron configurations for neutral atoms of elements in Periods 2 and 3.
- Master Difficulty Level: Question Groups 7-12 ... Identify the correct electron configurations for neutral atoms of elements in Periods 3,4, and 5.
- Wizard Difficulty Level: Question Groups 13-18 ... Identify the correct electron configurations for ions of elements in Periods 3 and 4.
The questions from each group are shown below. Teachers are encouraged to view the questions in order to judge which difficulty levels are most appropriate for their classes. We recommend providing students two or more options.
The Physics Classroom grants teachers and other users the right to print these questions for private use. Users are also granted the right to copy the text and modify it for their own use. However, this document should not be uploaded to other servers for distribution to and/or display by others. The Physics Classroom website should remain the only website or server from which the document is distributed or displayed. We also provide a PDF that teachers can use under the same conditions. We have included a link to the PDF near the bottom of this page.
Enthalpy Change
Apprentice Difficulty Level
Question Group 1
Question 1
The ∆H for the following reaction is -88 kJ.
PCl
3(g) + Cl
2(g) → PCl
5(g)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
2 PCl
3(g). + 2 Cl
2(g)→ 2 PCl
5(g))
PCl
5(g) → PCl
3(g) + Cl
2(g)
3 PCl
5(g) → 3 PCl
3(g) + 3 Cl
2(g)
5 PCl
3(g) + 5 Cl
2(g) → 5 PCl
5(g)
Question 2
The ∆H for the following reaction is -342 kJ.
Fe
(s) + Cl
2(g) → FeCl
2(s)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
2 Fe
(s) + 2 Cl
2(g) → 2 FeCl
2(s)
FeCl
2(s) → Fe
(s) + Cl
2(g)
3 FeCl
2(s) → 3 Fe
(s) + 3 Cl
2(g)
5 Fe
(s) + 5 Cl
2(g) → 5 FeCl
2(s)
Question 3
The ∆H for the following reaction is -394 kJ.
C
(s) + O
2(g) → CO
2(g)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
2 C
(s) + 2 O
2(g) → 2 CO
2(g)
CO
2(g) → C
(s) + O
2(g)
3 CO
2(g) → 3 C
(s) + 3 O
2(g)
5 C
(s) + 5 O
2(g)→ 5 CO
2(g)
Question Group 2
Question 4
The ∆H for the following reaction is -570 kJ.
2 H
2(g) + O
2(g) → 2 H
2O
(l)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
6 H
2(g) + 3 O
2(g) → 6 H
2O
(l)
4 H
2O
(l)→ 4 H
2(g) + 2 O
2(g)
4 H
2(g) + 2 O
2(g) → 4 H
2O
(l)
6 H
2O
(l) → 6 H
2(g) + 3 O
2(g)
Question 5
The ∆H for the following reaction is -565 kJ.
2 CO
(g) + O
2(g) → 2 CO
2(g)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
6 CO
(g) + 3 O
2(g) → 6 CO
2(g)
4 CO
2(g) → 4 CO
(g) + 2 O
2(g)
4 CO
(g) + 2 O
2(g) → 4 CO
2(g)
6 CO
2(g) → 6 CO
(g) + 3 O
2(g)
Question 6
The ∆H for the following reaction is -537 kJ.
H
2(g) + F
2(g) → 2 HF
(g)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
3 H
2(g) + 3 F
2(g) → 6 HF
(g)
4 HF
(g) → 2 H
2(g) + 2 F
2(g)
2 H
2(g) + 2 F
2(g) → 4 HF
(g)
6 HF
(g) → 3 H
2(g) + 3 F
2(g)
Question Group 3
Question 7
The ∆H for the following reaction is 180 kJ.
N
2(g) + O
2(g) → 2 NO
(g)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
4 N
2(g) + 4 O
2(g) → 8 NO
(g)
4 NO
(g) → 2 N
2(g) + 2 O
2(g)
6 NO
(g) → 3 N
2(g) + 3 O
2(g)
2 N
2(g) + 2 O
2(g) → 4 NO
(g)
Question 8
The ∆H for the following reaction is 566 kJ.
2 CO
2(g) → 2 CO
(g) + O
2(g)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
8 CO
2(g) → 8 CO
(g) + 4 O
2(g)
4 CO
(g) + 2 O
2(g) → 4 CO
2(g)
6 CO
(g) + 3 O
2(g) → 6 CO
2(g)
4 CO
2(g) → 4 CO
(g) + 2 O
2(g)
Question 9
The ∆H for the following reaction is -1686 kJ.
2 W
(s) + 3 O
2(g) → 2 WO
3(s)
Determine the ∆H (in kJ) for the related reactions below. (Give attention to the +/- sign).
8 W
(s) + 12 O
2(g) → 8 WO
3(s)
4 WO
3(s) → 4 W
(s) + 6 O
2(g)
6 WO
3(s) → 6 W
(s) + 9 O
2(g)
4W
(s) + 6 O
2(g) → 4 WO
3(s)
Question Group 4
Question 10
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
PCl
5(g)→PCl
3(g) + Cl
2(g) Δ
H= +88 kJ
Fe
(s)+ Cl
2(s) ⟶ FeCl
2(s) ΔH=−341.8kJ
C
(s) + O
2(g) ⟶ CO
2(g) DH = -393.5 kJ
Question 11
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
C
(s) + O
2(g) ⟶ CO
2(g) DH = -393.5 kJ
PCl
5(g)→PCl
3(g) + Cl
2(g) Δ
H= +88 kJ
Fe
(s)+ Cl
2(s) ⟶ FeCl
2(s) ΔH=−341.8kJ
Question 12
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
Fe
(s)+ Cl
2(s) ⟶ FeCl
2(s) ΔH=−341.8kJ
C
(s) + O
2(g) ⟶ CO
2(g) DH = -393.5 kJ
PCl
5(g)→PCl
3(g) + Cl
2(g) Δ
H= +88 kJ
Question Group 5
Question 13
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
2 H
2(g)+ O
2(g)→2 H
2O
(l) Δ
H= −570 kJ
2 CO
2(g) → 2 CO(g) + O
2(g) Δ
H= +565 kJ
H
2(g) +F
2(g) → 2 HF
(g) ∆H = -537kJ
Question 14
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
H
2(g) +F
2(g) → 2 HF
(g) ∆H = -537kJ
2 H
2(g)+ O
2(g)→2 H
2O
(l) Δ
H= −570 kJ
2 CO
2(g) → 2 CO(g) + O
2(g) Δ
H= +565 kJ
Question 15
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
2 CO
2(g) → 2 CO(g) + O
2(g) Δ
H= +565 kJ
H
2(g) +F
2(g) → 2 HF
(g) ∆H = -537kJ
2 H
2(g)+ O
2(g)→2 H
2O
(l) Δ
H= −570 kJ
Question Group 6
Question 16
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
N
2(g) + O
2(g) →2 NO
(g) DH= 180 kJ
2 CO
2(g) ⟶ 2 CO
(g) + O
2(g) DH = +566.0 kJ
2 W
(s) + 3 O
2(g) ⟶2 WO
3(s) DH = -1686 kJ
Question 17
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
2 W
(s) + 3 O
2(g) ⟶2 WO
3(s) DH = -1686 kJ
N
2(g) + O
2(g) →2 NO
(g) DH= 180 kJ
2 CO
2(g) ⟶ 2 CO
(g) + O
2(g) DH = +566.0 kJ
Question 18
The ∆H values for three chemical equations is shown. Adjust the equation so that the energy term (kJ) is located in the equation. Locate it on either the reactant or the product side.
2 CO
2(g) ⟶ 2 CO
(g) + O
2(g) DH = +566.0 kJ
2 W
(s) + 3 O
2(g) ⟶2 WO
3(s) DH = -1686 kJ
N
2(g) + O
2(g) →2 NO
(g) DH= 180 kJ
Master Difficulty Level
Question Group 7
Question 19
Students are studying the reaction: 2 H
2(g) + O
2(g) ⟶ 2 H
2O
(l)
Their calorimetry methods indicate that 61 kJ of heat is released to the surroundings when 0.250 mol of H
2 reacts. Use their data to determine the enthalpy change of the three given reactions.
2 H
2(g) + O
2(g) ⟶ 2 H
2O
(l) ∆H = _____________ kJ
4 H
2(g) + 2 O
2(g) ⟶4 H
2O
(l) ∆H = _____________ kJ
6 H
2(g) + 3 O
2(g) ⟶6 H
2O
(l) ∆H = _____________ kJ
Question 20
Students are studying the reaction: 2 H
2(g) + O
2(g) ⟶ 2 H
2O
(l)
Their calorimetry methods indicate that 121 kJ of heat is released to the surroundings when 0.500 mol of H
2reacts. Use their data to determine the enthalpy change of the three given reactions.
2 H
2(g) + O
2(g) ⟶ 2 H
2O
(l) ∆H = _____________ kJ
4 H
2(g) + 2 O
2(g) ⟶4 H
2O
(l) ∆H = _____________ kJ
6 H
2(g) + 3 O
2(g) ⟶6 H
2O
(l) ∆H = _____________ kJ
Question 21
Students are studying the reaction: 2 H
2(g) + O
2(g) ⟶ 2 H
2O
(l)
Their calorimetry methods indicate that 968 kJ of heat is released to the surroundings when 2.00 mol of O
2 reacts. Use their data to determine the enthalpy change of the three given reactions.
2 H
2(g) + O
2(g) ⟶ 2 H
2O
(l) ∆H = _____________ kJ
4 H
2(g) + 2 O
2(g) ⟶4 H
2O
(l) ∆H = _____________ kJ
6 H
2(g) + 3 O
2(g) ⟶6 H
2O
(l) ∆H = _____________ kJ
Question Group 8
Question 22
Students are studying the reaction: N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g)
Their calorimetry methods indicate that 23 kJ of heat is released to the surroundings when 0.250 mol of N
2reacts. Use their data to determine the enthalpy change of the three given reactions.
N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g) ∆H = _____________ kJ
2 N
2(g) + 6 H
2(g) ⟶ 4 NH
3(g) ∆H = _____________ kJ
3 N
2(g) + 9 H
2(g) ⟶ 6 NH
3(g) ∆H = _____________ kJ
Question 23
Students are studying the reaction: N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g)
Their calorimetry methods indicate that 46 kJ of heat is released to the surroundings when 0.500 mol of N
2reacts. Use their data to determine the enthalpy change of the three given reactions.
N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g) ∆H = _____________ kJ
2 N
2(g) + 6 H
2(g) ⟶ 4 NH
3(g) ∆H = _____________ kJ
3 N
2(g) + 9 H
2(g) ⟶ 6 NH
3(g) ∆H = _____________ kJ
Question 24
Students are studying the reaction: N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g)
Their calorimetry methods indicate that 46 kJ of heat is released to the surroundings when 1.50 mol of H
2reacts. Use their data to determine the enthalpy change of the three given reactions.
N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g) ∆H = _____________ kJ
2 N
2(g) + 6 H
2(g) ⟶ 4 NH
3(g) ∆H = _____________ kJ
3 N
2(g) + 9 H
2(g) ⟶ 6 NH
3(g) ∆H = _____________ kJ
Question Group 9
Question 25
Students are studying the reaction: 2 WO
2(s) + O
2(g) ⟶ 2 WO
3(s)
Their calorimetry methods indicate that 63 kJ of heat is released to the surroundings when 0.250 mol of WO
2reacts. Use their data to determine the enthalpy change of the three given reactions.
2 WO
2(s) + O
2(g) ⟶ 2 WO
3(s) ∆H = _____________ kJ
4 WO
2(s) + 2 O
2(g) ⟶ 4 WO
3(s) ∆H = _____________ kJ
6 WO
2(s) + 3 O
2(g) ⟶ 6 WO
3(s) ∆H = _____________ kJ
Question 26
Students are studying the reaction: 2 WO
2(s) + O
2(g) ⟶ 2 WO
3(s)
Their calorimetry methods indicate that 126 kJ of heat is released to the surroundings when 0.500 mol of WO
2reacts. Use their data to determine the enthalpy change of the three given reactions.
2 WO
2(s) + O
2(g) ⟶ 2 WO
3(s) ∆H = _____________ kJ
4 WO
2(s) + 2 O
2(g) ⟶ 4 WO
3(s) ∆H = _____________ kJ
6 WO
2(s) + 3 O
2(g) ⟶ 6 WO
3(s) ∆H = _____________ kJ
Question 27
Students are studying the reaction: 2 WO
2(s) + O
2(g) ⟶ 2 WO
3(s)
Their calorimetry methods indicate that 1010 kJ of heat is released to the surroundings when 2.00 mol of O
2reacts. Use their data to determine the enthalpy change of the three given reactions.
2 WO
2(s) + O
2(g) ⟶ 2 WO
3(s) ∆H = _____________ kJ
4 WO
2(s) + 2 O
2(g) ⟶ 4 WO
3(s) ∆H = _____________ kJ
6 WO
2(s) + 3 O
2(g) ⟶ 6 WO
3(s) ∆H = _____________ kJ
Question Group 10
Question 28
Students are studying the reaction: H
2(g) + Cl
2(g) ⟶ 2 HCl
(g)
Their calorimetry methods indicate that 92 kJ of heat is released to the surroundings when 0.50 mol of H
2reacts. Use their data to determine the enthalpy change of the three given reactions.
H
2(g) + Cl
2(g) ⟶ 2 HCl
(g) ∆H = _____________ kJ
2 H
2(g) + 2 Cl
2(g) ⟶ 4 HCl
(g) ∆H = _____________ kJ
4 H
2(g) + 4 Cl
2(g) ⟶ 8 HCl
(g) ∆H = _____________ kJ
Question 29
Students are studying the reaction: H
2(g) + Cl
2(g) ⟶ 2 HCl
(g)
Their calorimetry methods indicate that 46 kJ of heat is released to the surroundings when 0.250 mol of H
2reacts. Use their data to determine the enthalpy change of the three given reactions.
H
2(g) + Cl
2(g) ⟶ 2 HCl
(g) ∆H = _____________ kJ
2 H
2(g) + 2 Cl
2(g) ⟶ 4 HCl
(g) ∆H = _____________ kJ
4 H
2(g) + 4 Cl
2(g) ⟶ 8 HCl
(g) ∆H = _____________ kJ
Question 30
Students are studying the reaction: H
2(g) + Cl
2(g) ⟶ 2 HCl
(g)
Their calorimetry methods indicate that 368 kJ of heat is released to the surroundings when 2.00 mol of Cl
2reacts. Use their data to determine the enthalphy change of the three given reactions.
H
2(g) + Cl
2(g) ⟶ 2 HCl
(g) ∆H = _____________ kJ
2 H
2(g) + 2 Cl
2(g) ⟶ 4 HCl
(g) ∆H = _____________ kJ
4 H
2(g) + 4 Cl
2(g) ⟶ 8 HCl
(g) ∆H = _____________ kJ
Question Group 11
Question 31
Students are studying the reaction: PCl
5(g) ⟶ PCl
3(g) + Cl
2(g)
Their calorimetry methods indicate that 22 kJ of heat is absorbed from the surroundings when 0.250 mol of PCl
5reacts. Use their data to determine the enthalpy change of the three given reactions.
PCl
5(g) ⟶ PCl
3(g) + Cl
2(g) ∆H = _____________ kJ
3 PCl
5(g) ⟶ 3 PCl
3(g) + 3 Cl
2(g) ∆H = _____________ kJ
5 PCl
5(g) ⟶ 5 PCl
3(g) + 5 Cl
2(g) ∆H = _____________ kJ
Question 32
Students are studying the reaction: PCl
5(g) ⟶ PCl
3(g) + Cl
2(g)
Their calorimetry methods indicate that 44 kJ of heat is absorbed from the surroundings when 0.500 mol of PCl
5reacts. Use their data to determine the enthalpy change of the three given reactions.
PCl
5(g) ⟶ PCl
3(g) + Cl
2(g) ∆H = _____________ kJ
3 PCl
5(g) ⟶ 3 PCl
3(g) + 3 Cl
2(g) ∆H = _____________ kJ
5 PCl
5(g) ⟶ 5 PCl
3(g) + 5 Cl
2(g) ∆H = _____________ kJ
Question 33
Students are studying the reaction: PCl
5(g) ⟶ PCl
3(g) + Cl
2(g)
Their calorimetry methods indicate that 176 kJ of heat is absorbed from the surroundings when 2.00 mol of PCl
5reacts. Use their data to determine the enthalpy change of the three given reactions.
PCl
5(g) ⟶ PCl
3(g) + Cl
2(g) ∆H = _____________ kJ
3 PCl
5(g) ⟶ 3 PCl
3(g) + 3 Cl
2(g) ∆H = _____________ kJ
5 PCl
5(g) ⟶ 5 PCl
3(g) + 5 Cl
2(g) ∆H = _____________ kJ
Question Group 12
Question 34
Students are studying the reaction: C
(s) + 2 F
2(g) ⟶ CF
4(g)
Their calorimetry methods indicate that 340 kJ of heat is released to the surroundings when 0.500 mol of Creacts. Use their data to determine the enthalpy change of the three given reactions.
C
(s) + 2 F
2(g) ⟶ CF
4(g) ∆H = _____________ kJ
2 C
(s) + 4 F
2(g) ⟶ 2 CF
4(g) ∆H = _____________ kJ
5 C
(s) + 10 F
2(g) ⟶ 5 CF
4(g) ∆H = _____________ kJ
Question 35
Students are studying the reaction: C
(s) + 2 F
2(g) ⟶ CF
4(g)
Their calorimetry methods indicate that 170 kJ of heat is released to the surroundings when 0.500 mol of F
2reacts. Use their data to determine the enthalpy change of the three given reactions.
C
(s) + 2 F
2(g) ⟶ CF
4(g) ∆H = _____________ kJ
2 C
(s) + 4 F
2(g) ⟶ 2 CF
4(g) ∆H = _____________ kJ
5 C
(s) + 10 F
2(g) ⟶ 5 CF
4(g) ∆H = _____________ kJ
Question 36
Students are studying the reaction: C
(s) + 2 F
2(g) ⟶ CF
4(g)
Their calorimetry methods indicate that 1360 kJ of heat is released to the surroundings when 2.00 mol of Creacts. Use their data to determine the enthalpy change of the three given reactions.
C
(s) + 2 F
2(g) ⟶ CF
4(g) ∆H = _____________ kJ
2 C
(s) + 4 F
2(g) ⟶ 2 CF
4(g) ∆H = _____________ kJ
5 C
(s) + 10 F
2(g) ⟶ 5 CF
4(g) ∆H = _____________ kJ
Wizard Difficulty Level
Question Group 13
Question 37
Students are studying the reaction: N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g)
Their calorimetry methods indicate that 46.0 kJ of heat is released to the surroundings when 14.0 grams of N
2reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question 38
Students are studying the reaction: N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g)
Their calorimetry methods indicate that 46.0 kJ of heat is released to the surroundings when 3.00 grams of H
2reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question 39
Students are studying the reaction: N
2(g) + 3 H
2(g) ⟶ 2 NH
3(g)
Their calorimetry methods indicate that 184 kJ of heat is released to the surroundings when 12.0 grams of N
2reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question Group 14
Question 40
Students are studying the reaction: C
(s) + 2 F
2(g) ⟶ CF
4(g)
Their calorimetry methods indicate that 340 kJ of heat is released to the surroundings when 0.500 grams of C reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question 41
Students are studying the reaction: C
(s) + 2 F
2(g) ⟶ CF
4(g)
Their calorimetry methods indicate that 170 kJ of heat is released to the surroundings when 0.500 grams of F
2reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question 42
Students are studying the reaction: C
(s) + 2 F
2(g) ⟶ CF
4(g)
Their calorimetry methods indicate that 340 kJ of heat is released to the surroundings when 1.00 grams of F
2reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question Group 15
Question 43
Students are studying the reaction: C
(s) + O
2(g) → CO
2(g)
Their calorimetry methods indicate that 197 kJ of heat is released to the surroundings when 6.00 grams of C reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question 44
Students are studying the reaction: C
(s) + O
2(g) → CO
2(g)
Their calorimetry methods indicate that 98.5 kJ of heat is released to the surroundings when 8.00 grams of O
2reacts. Use their data to determine the moles of reactant and the enthalpy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
moles of reactant:‑
__________________
∆H = _____________________ kJ
Question 45
Students are studying the reaction: C
(s) + O
2(g) → CO
2(g)
Their calorimetry methods indicate that 197 kJ of heat is released to the surroundings when 16.0 grams of O
2reacts. Use their data to determine the moles of reactant and the enthalphy change (in kJ) of the given reaction. Include the proper +/- sign on ∆H.
enthalpymoles of reactant:‑
__________________
∆H = _____________________ kJ