R1.3 Energy from fuels
15 revision questions with answers for R1.3 Energy from fuels, marked SL. Read them here, or play the set as a class game on the projector. Free to host, and students join with a code.
Products of the complete combustion of a hydrocarbon?
- CO and H₂O
- CO₂ and H₂ORight answer
- C and H₂
- CO₂ and H₂
What this set covers
Fuels and energy: complete and incomplete combustion, balancing combustion equations, specific energy against energy density, fossil fuels, biofuels such as ethanol and methane, and hydrogen fuel cells.
- Common mix-up
- Students often mix up specific energy and energy density: specific energy is energy per unit mass in kJ g⁻¹, whereas energy density is per unit volume.
- Revision tip
- Calculate the specific energy of a fuel from ΔHc and molar mass, then compare coal with natural gas by CO₂ released per unit energy.
All 15 questions and answers
Products of the complete combustion of a hydrocarbon?
Answer: CO₂ and H₂O
Toxic gas formed by incomplete combustion?
Answer: Carbon monoxide
Black particulate formed by incomplete combustion?
Answer: Soot
Coefficient of O₂ in the balanced complete combustion of CH₄?
Answer: 2
Coefficient of O₂ in the balanced complete combustion of C₃H₈?
Answer: 5
Energy released per unit mass of a fuel, in kJ g⁻¹?
Answer: Specific energy
Energy released per unit volume of a fuel?
Answer: Energy density
Specific energy of a fuel with ΔHc = −2200 kJ mol⁻¹ and M = 44 g mol⁻¹?
Answer: 50 kJ g⁻¹
Fossil fuel releasing the most CO₂ per kJ of energy?
Answer: Coal
Fuel made from recently living biomass?
Answer: Biofuel
Biofuel made by fermenting sugars with yeast?
Answer: Ethanol
Main fuel gas made by anaerobic digestion of organic waste?
Answer: Methane
Burning a biofuel is close to carbon-neutral because its CO₂ was absorbed during…?
Answer: Photosynthesis
Device converting a continuously supplied fuel's chemical energy directly into electricity?
Answer: Fuel cell
Only product of a hydrogen–oxygen fuel cell?
Answer: Water
Play it as a class game
Play this set opens it in splycr, where you can host it for your class straight away. Hosting needs no account: put the room code on the projector, and students join from a phone with the code and their first name. Each question plays as multiple choice, and the three wrong options were written for that question.