Bond Energy Practice – 16-Problem Chemistry Set

Students will calculate the enthalpy of reaction (Hrxn) using the bond-energy method: bonds broken minus bonds formed.

Students will apply standard bond-energy values (e.g., C-H, O=O, N-H) to balanced chemical equations.

Students will determine molecular structure from a chemical formula or equation in order to count the bonds broken and formed.

Relabel the two formula-only entries as bond-energy sums rather than reaction enthalpies; the nitrate example needs explicit treatment of resonance and the approximation being used.

In the first key, item 1 needs 2(H–H), and item 3 needs N≡N and 6(N–H) in its symbolic setup. Their following numerical lines already use the corresponding multiplicities.

Use parentheses around the entire bonds-formed sum, state the reaction basis for units, and distinguish an approximate bond-energy calculation from an experimentally measured enthalpy.

Bond-energy calculation — applying Hrxn = bonds broken − bonds formed to balanced chemical equations.

Molecular structure analysis — identifying and counting bond types (single, double, triple) in reactants and products.

Quantitative problem solving — substituting tabulated bond-energy values (kJ/mol) and completing multi-step arithmetic to reach a signed final answer.