Energy resources and sustainabilityIB MYP Chemistry: Mind map

Exam questions on Energy resources and sustainability

1. A city bus company in Japan is trialling buses that run on hydrogen. The hydrogen is made by electrolysis of water, using electricity from an offshore wind farm. The only substance released from the bus exhausts is water vapour.
   Outline two disadvantages of using hydrogen as a fuel for buses.2 marks
2. Students in São Paulo, Brazil, compare two fuels for cars. Ethanol is made by fermenting sugar from sugar cane. Petrol contains octane, which comes from crude oil. The students use this data: burning one mole of ethanol releases 1367 kJ and its relative molecular mass is 46; burning one mole of octane releases 5470 kJ and its relative molecular mass is 114.
   Calculate the energy released per gram of octane and state which fuel releases more energy per gram.2 marks
3. A school science club in Kenya investigates which liquid fuel releases more energy per gram. They burn ethanol and then paraffin in a spirit burner under a metal can containing 100 g of water. They record the starting and final water temperatures and the mass of fuel burned. Results: ethanol, temperature rise 18.0 °C, mass burned 1.50 g; paraffin, temperature rise 30.0 °C, mass burned 1.40 g. The specific heat capacity of water is 4.2 J g⁻¹ °C⁻¹.
   Identify the independent variable, the dependent variable and one control variable in the club's investigation.3 marks