Fuels and biogas_Chemistry Past Exam Paper Questions VCE

Why is biogas considered a renewable energy source but coal seam gas is not?

Biogas-produced from the decomposition of organic matter Coal seam gas-extracted from underground coal seams through drilling and hydraulic fracturing

What is a fuel cell?

A fuel cell is a device that constantly feeds fuel and an oxidizer into it when the two react chemically, producing electricity, water, and heat as by-products.

Biodiesel and petrodiesel A. have different viscosities. B. have the same environmental impact. C. contain molecules with no polar groups. D. will flow easily through fuel lines in very cold climate conditions.

A. have different viscosities.

Galvanic cells and fuel cells have A. the same energy transformations and both are reversible. B. the same energy transformations and both produce heat. C. different energy transformations but galvanic cells produce electricity. D. different energy transformations but fuel cells use porous electrodes.

B. the same energy transformations and both produce heat.

Digesters use bacteria to convert organic waste into biogas, which contains mainly methane. Biogas was combusted to release some amount of energy which was used to heat of water in a tank. The initial temperature of the water was 25.0 degrees Celsius. State why this temperature may not be reached.

Because of the heat loss to the surroundings (conduction, convection and radiation) or through the walls of the tank or any present insulation.

Write the equation for the incomplete combustion of CH4 to produce carbon monoxide.

CH4 + 3/2 O2 -> CO2 + 2H2O

Write the thermochemical equation for the complete combustion of methane.

CH4(g) + 2O2(g) -> CO2(g) + 2H2O(g)

Unlike direct combustion of fuel, fuel cells A. can be recharged. B. do not produce greenhouse gases. C. require electrical energy to overcome the activation energy barrier. D. do not have direct contact between the oxidising and reducing agents.

D. do not have direct contact between the oxidising and reducing agents.

State how the environmental impact of using an ethanol fuel cell operating at 100 percent efficiency can be minimised.

Ethanol should be derived from sustainable sources such as biomass or agricultural waste. implementing technologies for capturing and storing the carbon dioxide produced during the operation of the fuel cell. optimizing the design and operation of the fuel cell system. The components of the fuel cell should be recycled to reduce the need for raw materials and to minimize waste generation.

Identify two aspects of electrode design that can improve the efficiency of a fuel cell.

Increased surface area and enhanced catalyst activity.