Bond energy: breaking takes energy, forming releases it
Grade 10 Science Worksheet
Circle the best answer, or write your answer on the line.
In H₂ + Cl₂ → 2 HCl, breaking bonds takes 679 kJ and forming bonds releases 864 kJ. Estimate ΔH, Ari?
In 2 H₂ + O₂ → 2 H₂O, breaking bonds takes 1370 kJ and forming bonds releases 1856 kJ. Estimate ΔH, Bo?
In N₂ + 3 H₂ → 2 NH₃, breaking bonds takes 2254 kJ and forming bonds releases 2340 kJ. Estimate ΔH, Esme?
In 2 H₂ + O₂ → 2 H₂O, how many O–H bonds form, Kira?
- 2
- 3
- 4
In N₂ + 3 H₂ → 2 NH₃, how many N–H bonds form, Luz?
- 3
- 6
- 2
Breaking takes 679 kJ and forming releases 864 kJ. Is the reaction exothermic or endothermic, Milo?
- Endothermic: breaking comes first
- Endothermic: forming gives more
- Exothermic: forming gives more
Why is a ΔH found from bond energies only an estimate, Noah?
- Energy isn't conserved
- The table gives averages
- Bonds can't be measured
On an energy diagram, which way does the bond-breaking step go, Ren?
- Downhill
- Flat
- Uphill
O–H has a bond energy of 464 kJ/mol and H–H has 436. Which takes more energy to break, Tala?
- O–H
- They're equal
- H–H
Why does burning methane release energy overall, Zee?
- Its products' bonds release more
- Methane has no bonds in it
- Oxygen's bonds release energy
