Methane, CH4\mathrm{CH_{4}}CH4, is a greenhouse gas.
Landfill sites release methane when waste decomposes.
Over 100 years, releasing 1 tonne of methane into the atmosphere has about the same warming effect as releasing 28 tonnes of carbon dioxide.
Describe how methane molecules in the atmosphere make the Earth's surface warmer.
Use ideas about radiation.
A landfill site collects 500 tonnes of methane each year. The methane is burned to generate electricity.
CH4+2O2→CO2+2H2O \mathrm{CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O} CH4+2O2→CO2+2H2OCalculate the mass of carbon dioxide made when 500 tonnes of methane burns completely.
Relative atomic masses (Ar): C = 12.0 H = 1.0 O = 16.0
The manager of the landfill site says:
"Burning the methane is bad for the climate, because it makes a greater mass of carbon dioxide than the mass of methane we started with."
Evaluate the manager's statement. Use your answer to (b)(i) and the information in the question.
Suggest one other way to reduce the amount of methane released by human activity.
51 exam-style questions on OCR GCSE Chemistry 6.3 Interpreting and interacting with earth systems, covering 6.3.1 Formation and evolution of the atmosphere, 6.3.2 The greenhouse effect and climate change, 6.3.3 Sources and problems of atmospheric pollutants, and 6.3.4 Producing potable water. Each one has a worked solution and a mark scheme showing where the marks go.