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title: "The complete combustion of a gaseous hydrocarbon in excess oxygen releases thermal energy according to the general balanced equation below:  \\[ \\text{C}_x\\text{H}_y\\text{(g)} + \\left(x + \\dfrac{y}{4}\\right)\\text{O}_2\\text{(g)} \\rightarrow x\\,\\text{CO}_2\\text{(g)} + \\dfrac{y}{2}\\,\\text{H}_2\\text{O(g)} \\quad \\Delta H^\\circ_{\\text{comb}} < 0 \\]  Let \\(q_{\\text{O}_2}\\) represent the magnitude of the energy released per mole of \\(\\text{O}_2\\text{(g)}\\) consumed, and let \\(q_{\\text{H}_2\\text{O}}\\) represent the magnitude of the energy released per mole of \\(\\text{H}_2\\text{O(g)}\\) produced during the reaction. If an experiment determines that the ratio \\(\\dfrac{q_{\\text{O}_2}}{q_{\\text{H}_2\\text{O}}} = \\dfrac{2}{3}\\), which of the following could be the identity of the hydrocarbon?"
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url: "https://nerd-notes.com/ubq/123813/"
date_modified: "2026-09-28T12:30:23+00:00"
---

# The complete combustion of a gaseous hydrocarbon in excess oxygen releases thermal energy according to the general balanced equation below:

\[ \text{C}_x\text{H}_y\text{(g)} + \left(x + \dfrac{y}{4}\right)\text{O}_2\text{(g)} \rightarrow x\,\text{CO}_2\text{(g)} + \dfrac{y}{2}\,\text{H}_2\text{O(g)} \quad \Delta H^\circ_{\text{comb}} < 0 \]

Let \(q_{\text{O}_2}\) represent the magnitude of the energy released per mole of \(\text{O}_2\text{(g)}\) consumed, and let \(q_{\text{H}_2\text{O}}\) represent the magnitude of the energy released per mole of \(\text{H}_2\text{O(g)}\) produced during the reaction. If an experiment determines that the ratio \(\dfrac{q_{\text{O}_2}}{q_{\text{H}_2\text{O}}} = \dfrac{2}{3}\), which of the following could be the identity of the hydrocarbon?

The complete combustion of a gaseous hydrocarbon in excess oxygen releases thermal energy according to the general balanced equation below:

\[ \text{C}_x\text{H}_y\text{(g)} + \left(x + \dfrac{y}{4}\right)\text{O}_2\text{(g)} \rightarrow x\,\text{CO}_2\text{(g)} + \dfrac{y}{2}\,\text{H}_2\text{O(g)} \quad \Delta H^\circ_{\text{comb}} < 0 \]

Let \(q_{\text{O}_2}\) represent the magnitude of the energy released per mole of \(\text{O}_2\text{(g)}\) consumed, and let \(q_{\text{H}_2\text{O}}\) represent the magnitude of the energy released per mole of \(\text{H}_2\text{O(g)}\) produced during the reaction. If an experiment determines that the ratio \(\dfrac{q_{\text{O}_2}}{q_{\text{H}_2\text{O}}} = \dfrac{2}{3}\), which of the following could be the identity of the hydrocarbon?

- **A.** \(\text{CH}_4\text{(g)}\)
- **B.** \(\text{C}_2\text{H}_6\text{(g)}\)
- **C.** \(\text{C}_3\text{H}_6\text{(g)}\)
- **D.** \(\text{C}_3\text{H}_8\text{(g)}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123813/*