A technician uses the model in Fig. 1 during a safety briefing at a biogas plant. It represents methane, the simplest compound in the alkane series. The bla...
Question 1 Report
A technician uses the model in Fig. 1 during a safety briefing at a biogas plant. It represents methane, the simplest compound in the alkane series. The black sphere represents a carbon atom and the four small spheres represent hydrogen atoms. Methane and ethane are hydrocarbons because their molecules contain carbon and hydrogen only. If methane leaks into a building, it can mix with air and undergo a rapid combustion reaction when a spark is present. The technician asks trainees to use the model, rather than the word methane, when recording the formula in their report.
(a) Name the hydrocarbon shown in Fig. 1. [1]
(b) Give the molecular formula of this compound. [1]
(c) State why methane is described as a saturated compound. [1]
(d) Complete the word equation for complete combustion of methane.
methane + oxygen → __________ + __________ [2]
(e) State one hazard of a methane leak in an enclosed space. [1]
Answer Details
(a) The model shows one carbon atom bonded to four hydrogen atoms. This hydrocarbon is methane. [1]
(b) Counting the atoms gives \(\mathrm{CH_4}\). [1]
(c) Methane is saturated because it has no carbon-carbon multiple bond. More generally, saturated hydrocarbons have only single carbon-carbon bonds. [1]
(d) In complete combustion, the carbon forms carbon dioxide and the hydrogen forms water:
methane + oxygen → carbon dioxide + water. [2]
(e) Methane is flammable. A leak can mix with air to form an explosive mixture, so a spark may cause an explosion. [1]
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