The displayed formula of ethane is shown. Ethane is a colourless gas used in the chemical industry. Use the diagram to write down the molecular formula of e...
Question 1 Report
The displayed formula of ethane is shown. Ethane is a colourless gas used in the chemical industry. Use the diagram to write down the molecular formula of ethane.
Answer Details
Count directly from the displayed formula. Two carbon atoms are joined by a single bond, and each carbon carries three hydrogen atoms, using its remaining three bonds.
That gives 2 carbons and \(3 + 3 = 6\) hydrogens, so the molecular formula is \(\text{C}_2\text{H}_6\). It agrees with the alkane general formula \(\text{C}_n\text{H}_{2n+2}\) for \(n = 2\), since \((2 \times 2) + 2 = 6\).
\(\text{C}_2\text{H}_4\) is ethene, an alkene, and would need a double bond between the carbons, which is not drawn. \(\text{C}_2\text{H}_2\) is ethyne and needs a triple bond. \(\text{CH}_4\) has only one carbon and ignores half the diagram. In every valid structure each carbon must show exactly four bonds; use that as your check.
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