Alkenes

5 marks · Easy

This question is about alkenes with up to four carbon atoms and their physical properties.

(a)

Draw the displayed formula of ethene.

[1 mark]

(b)

Give the general formula for all alkenes.

[1 mark]

(c)

State the physical state of propene and butene at room temperature.

[2 marks]

(d)

Complete this sentence: "The physical state of small alkenes (up to butene) at room temperature is similar to the physical state of small _____."

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) — · must show C=C double bond between two carbons, each C has 2 H atoms

(b) CnH2n · must show CnH2n

(d) alkanes · must show alkanes

Show mark scheme and worked solution

Marking points

A1 (a) · 1 mark · Correct displayed formula of ethene showing C=C double bond and 2 H atoms on each C.

B1 (b) · 1 mark · CnH2n as general formula.

C1 (c) · 1 mark · Propene is a gas at room temperature.

C2 (c) · 1 mark · Butene is a gas at room temperature.

D1 (d) · 1 mark · Correctly completes with 'alkanes'.

Worked solution

a) The displayed formula of ethene is:

b) The general formula for alkenes is CnH2n.

c) Both propene and butene are gases at room temperature.

d) The physical state is similar to small alkanes: "alkanes" completes the sentence.