16. Different are used for different purposes. (a) Ethanol, C2H5OH, can be used as a fuel in some camping stoves. (i) The enthalpy of combustion of ethanol given in the data booklet is kJ mol−1. this value, calculate the mass of ethanol, in g, −1367 required to raise the temperature of 500 g of water from 18 °C to 100 °C. Show your working clearly. (3) (ii) Suggest two reasons why less energy is obtained from burning ethanol in the camping stove than is predicted from its enthalpy of combustion. (2) (b) Petrol is a fuel used in cars. A car has a 50·0 litre petrol tank. Calculate the energy, in kJ, released by the complete combustion of one tank of petrol. (2) 17. Hydrogen has been named as a for the future’. In a recent article ‘fuel researchers reported success in making hydrogen from glycerol: C3H8O3(l) CO2(g) + CH4(g) + H2(g) → (a) Balance this equation. (1) (b) The enthalpy of formation of glycerol is the enthalpy change for the reaction: 3C(s) + 4H2(g) + 1½O2(g) C3H8O3(l) → (graphite) Calculate the enthalpy of formation of glycerol, in kJ mol–1, information from the data booklet and the following data. C3H8O3(l) + 3½O2(g) 3CO2(g) + 4H2O(l) = kJ mol–1 ΔH –1654 → Show your working clearly. (2)
16. Different are used for different purposes. (a) Ethanol, C2H5OH, can be used as a fuel in some camping stoves. (i) The enthalpy of combustion of ethanol given in the data booklet is −1367 kJ mol−1. this value, calculate the mass of ethanol, in g, required to raise the temperature of 500 g of water from 18 °C to 100 °C. Show your working clearly. (3) (ii) Suggest two reasons why less energy is obtained from burning ethanol in the camping stove than is predicted from its enthalpy of combustion. (2) (b) Petrol is a fuel used in cars. A car has a 50·0 litre petrol tank. Calculate the energy, in kJ, released by the complete combustion of one tank of petrol. (2) 17. Hydrogen has been named as a ‘fuel for the future’. In a recent article researchers reported success in making hydrogen from glycerol: C3H8O3(l) → CO2(g) + CH4(g) + H2(g) (a) Balance this equation. (1) (b) The enthalpy of formation of glycerol is the enthalpy change for the reaction: 3C(s) + 4H2(g) + 1½O2(g) → C3H8O3(l) (graphite) Calculate the enthalpy of formation of glycerol, in kJ mol–1, information from the data booklet and the following data. C3H8O3(l) + 3½O2(g) → 3CO2(g) + 4H2O(l) ΔH = –1654 kJ mol–1 Show your working clearly. (2)
Unit-3-Exam-Level-Questions-1.docx