Free Printable WorksheetScienceGrade 11Science CurriculumNGSS HS-PS1-4; AP Chem Units 6 and 9; CCSS HSN-Q.A.1-3 and HSA-CED.A.1-4

11.80 Hess's Law Worksheet

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Worksheet Overview & Skills Covered

Core academic competencies and curriculum alignment

This Chemistry Science worksheet provides structured practice on 11.80 Hess's Law. Students are guided through targeted exercises that build foundational understanding, computational accuracy, and critical thinking skills.

Hess's Law: Use Hess's Law to combine reactions and calculate overall enthalpy changes from known reaction enthalpies. Aligned to NGSS, CCSS, AP Chemistry/Pre-AP Chemistry, and representative state chemistry framework crosswalks NGSS HS-PS1-4; AP Chem Units 6 and 9; CCSS HSN-Q.A.1-3 and HSA-CED.A.1-4 - Hess's Law Chemistry Standards Crosswalk: National: NGSS HS-PS1-4; AP Chem Units 6 and 9; CCSS HSN-Q.A.1-3 and HSA-CED.A.1-4. State frameworks: TX TEKS 112.43(c)(13); FL SC.912.P.10.4, P.10.6; MA/CA/NY/NJ HS-PS1 energy standards; GA and VA thermochemistry/energy standards.

Whether you are an educator preparing classroom handouts, a tutor reinforcing weekly topics, or a parent supporting homeschool learning, this printable resource gives students the deliberate practice required to achieve subject fluency and master state standards.

Grade

Chemistry

Subject

Science

Domain

Science Curriculum

Formats

PDF & DOCX

Sample Practice Problems

Preview the types of problems and questions covered in this worksheet

Below are sample questions representative of the exercises included on this worksheet and related 11.80 Hess's Law skill assessments:

Problem 1Difficulty: Mastery

In a simplified thermochemistry table, these reactions are listed. (1) C4H6(g) + 11/2 O2(g) -> 4 CO2(g) + 3 H2O(l), Delta H = -2540 kJ; (2) H2(g) + 1/2 O2(g) -> H2O(l), Delta H = -286 kJ; (3) C4H10(g) + 13/2 O2(g) -> 4 CO2(g) + 5 H2O(l), Delta H = -2878 kJ; (4) CO(g) + 1/2 O2(g) -> CO2(g), Delta H = -283 kJ. Target: C4H6(g) + 2 H2(g) -> C4H10(g). What is Delta H when the equations are combined to make the target?

A-5990 kJ

B+52 kJ

C-5987 kJ

D-234 kJ

Solution & Explanation:After the equations are adjusted to match the target, the Delta H values are added: -2540 kJ - 572 kJ + 2878 kJ = -234 kJ. Equation 4 is not needed because its species do not cancel to the target.

Problem 2Difficulty: Mastery

The following equations are available for a Hess's Law calculation. (1) C2H2(g) + 5/2 O2(g) -> 2 CO2(g) + H2O(l), Delta H = -1300 kJ; (2) H2(g) + 1/2 O2(g) -> H2O(l), Delta H = -286 kJ; (3) C2H6(g) + 7/2 O2(g) -> 2 CO2(g) + 3 H2O(l), Delta H = -1560 kJ; (4) CO(g) + 1/2 O2(g) -> CO2(g), Delta H = -283 kJ. Target: C2H2(g) + 2 H2(g) -> C2H6(g). What is the enthalpy change for the reaction as written?

A-3432 kJ

B-26 kJ

C-312 kJ

D-3429 kJ

Solution & Explanation:Canceling the intermediate species requires that you use equation 1 as written, double equation 2, and reverse equation 3. The enthalpy sum is -1300 kJ - 572 kJ + 1560 kJ, which equals -312 kJ. Equation 4 is not needed because its species do not cancel to the target.

Problem 3Difficulty: Mastery

A researcher reports the following enthalpy changes for reactions as written. (1) C3H6(g) + 9/2 O2(g) -> 3 CO2(g) + 3 H2O(l), Delta H = -2058 kJ; (2) H2(g) + 1/2 O2(g) -> H2O(l), Delta H = -286 kJ; (3) C3H8(g) + 5 O2(g) -> 3 CO2(g) + 4 H2O(l), Delta H = -2220 kJ; (4) CO(g) + 1/2 O2(g) -> CO2(g), Delta H = -283 kJ. Target: C3H6(g) + H2(g) -> C3H8(g). What value of Delta H should be assigned to the target equation?

A-4564 kJ

B-124 kJ

C-4847 kJ

D+124 kJ

Solution & Explanation:Hess's Law uses the same operations on Delta H as on the equations. Here, use equation 1 as written, use equation 2 as written, and reverse equation 3, so the total is -2058 kJ - 286 kJ + 2220 kJ = -124 kJ. Equation 4 is not needed because its species do not cancel to the target.

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QWhat grade level and standards does this worksheet align with?

This worksheet is designed specifically for Chemistry Science students. It aligns with educational standard NGSS HS-PS1-4; AP Chem Units 6 and 9; CCSS HSN-Q.A.1-3 and HSA-CED.A.1-4 (National: NGSS HS-PS1-4; AP Chem Units 6 and 9; CCSS HSN-Q.A.1-3 and HSA-CED.A.1-4. State frameworks: TX TEKS 112.43(c)(13); FL SC.912.P.10.4, P.10.6; MA/CA/NY/NJ HS-PS1 energy standards; GA and VA thermochemistry/energy standards.).