A forensic team finds Fig. 1 on a label from a damaged solvent container. It shows the displayed formula of but-2-ene and a note that the liquid reacted wit...
Question 1 Report
A forensic team finds Fig. 1 on a label from a damaged solvent container. It shows the displayed formula of but-2-ene and a note that the liquid reacted with hydrogen in the presence of a nickel catalyst. The team must identify the product before deciding how to store the recovered liquid. Hydrogen is added across the double bond, producing a saturated hydrocarbon. This reaction is also used on some plant oils to alter their physical properties.
(a) Name the type of reaction between but-2-ene and hydrogen. [1]
(b) Complete the molecular formula of but-2-ene: C4H___. [1]
(c) Use the displayed formula to explain why the product has the formula C4H10. [5]
Answer Details
(a) The reaction is addition, also called hydrogenation. Hydrogen adds across the carbon-carbon double bond. [1]
(b) But-2-ene has formula \(\text{C}_4\text{H}_8\), so the missing number is 8. [1]
(c) But-2-ene contains four carbon atoms and eight hydrogen atoms, giving \(\text{C}_4\text{H}_8\). It has one carbon-carbon double bond. Hydrogen adds across this double bond, with one hydrogen atom bonding to each of the two carbon atoms. This adds two hydrogen atoms, giving \(\text{C}_4\text{H}_{10}\). [5]
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