Properties of hydrocarbons

This question is about hydrocarbons with six carbon atoms.

Compound A is a hydrocarbon:

Compound A

What is the systematic name of compound A ?

The table below shows incomplete information about two hydrocarbons.

Complete the table.

Compound B, CH₃CH=C(CH₃)CH₂CH₃, exists as E and Z stereoisomers.

Draw the structures of the E and Z stereoisomers of compound B.

Explain why compound B can form E and Z stereoisomers.

Hexane, C₆H₁₄, is used as a fuel.

1.0 mol of hexane is mixed with 6.0 mol of oxygen and combusted.

Construct an equation for the incomplete combustion of 1.0 mol of hexane with 6.0 mol of oxygen.

For complete combustion, 0.100 mol of an alkane requires 22.8 dm³ of O₂, measured at RTP.

Which alkane has undergone complete combustion?

A pentane

B hexane

C heptane

D octane

This question is about hydrocarbons.

The boiling points of some hydrocarbons containing 6 carbon atoms are shown below.

State and explain the trend in boiling points shown by these hydrocarbons.

2-methylpentane reacts with bromine by radical substitution.

A mixture of organic products is formed, including 3-bromo-2-methylpentane, and compounds A and B.

Complete the table below to show the mechanism for the formation of 3-bromo-2-methylpentane and three possible equations for termination.

In your equations, use structural or skeletal formulae and ‘dots’ (•) for the position of

Organic compound A is formed by the substitution of all 14 H atoms in 2-methylpentane by Br atoms.

Write the equation, using molecular formulae, for the formation of compound A from 2-methylpentane.

Organic compound B is formed by the substitution of some of the 14 H atoms in 2-methylpentane by Br atoms.

0.8649 g of compound B is heated until it is vaporised.

Under the conditions used:

• compound B has a volume of 72.0 cm³

• the molar gas volume is 40.0 dm³ mol^–1.

Determine a possible molecular formula of compound B.

Complete combustion of 0.050 mol of an alkane produces 5.40 g of H₂O.

What is the molecular formula of the alkane?

A C₂H₆

B C₃H₈

C C₄H₁₀

D C₅H₁₂

Which alkane has the highest boiling point?

A CH₃(CH₂)₅CH₃

B (CH₃)₃CCH(CH₃)₂

C CH₃(CH₂)₃CH(CH₃)₂

D (CH₃)₂CHCH₂CH(CH₃)₂

The relative molecular masses and boiling points of some fuels are shown in Table 22.1.

Write an equation for the incomplete combustion of heptane.

Explain the difference in the boiling points of the fuels in Table 22.1.

Fuel additives are often used to improve the combustion of a fuel.

Compound N is a fuel additive containing carbon, hydrogen and oxygen only.

Complete combustion of 1.71 g of compound N produces 2.97 g of CO₂ and 1.62 g of H₂O. The relative molecular mass of compound N is 76.0.

Calculate the molecular formula of N and suggest a possible structure for the compound.

compound N

Solketal has been investigated as a potential fuel additive.

Solketal is synthesised from propane-1,2,3-triol and a carbonyl compound.

Construct a balanced equation for this synthesis. Show structures for the organic compounds in your equation.

* A scientist is researching compounds that might be suitable as fuel additives. One of the compounds gives the analytical results below.

Elemental analysis by mass: C: 54.54%; H: 9.10%; O: 36.36%

Mass spectrum: Molecular ion peak at m / z = 132.0

¹H NMR spectrum in D₂O

The numbers by the peaks are the relative peak areas.

When the spectrum is run without D₂O, there are two additional peaks with the same relative peak areas at 11.0 ppm and 3.6 ppm.

Use the information provided to suggest a structure for the compound.

Show all your reasoning.

This question is about unsaturated hydrocarbons.

Compound A and compound B are isomers.

Compound A has a lower melting point than compound B.

Suggest why.

Compound C, CH₃CH₂CH=CHCH₂CH₂OH, exists as cis and trans stereoisomers.

Name compound C.

Define the term stereoisomers.

Draw the structures of the cis and trans stereoisomers of compound C.

The C=C group in an alkene contains a -bond.

Complete the diagram below to show how p-orbitals are involved in the formation of a -bond.

Compound D, shown below, reacts with hydrogen bromide by electrophilic addition. A mixture of two organic compounds, E and F, is formed.

compound D

Suggest how an HBr molecule can act as an electrophile.

Draw the structures of the two organic compounds E and F.

Outline the mechanism of the reaction between compound D and hydrogen bromide to form either compound E or compound F.

Include curly arrows and relevant dipoles.

Which of E or F is the major organic product?

Explain your answer.

Major organic product........

Explanation........

Myrcene, C₁₀H₁₆, is a naturally occurring hydrocarbon containing more than one carbon-carbon double bond.

Reaction of 204 mg of myrcene with hydrogen gas produces a saturated alkane.

Calculate the volume of hydrogen gas, in cm³ and measured at RTP, needed for this reaction.

Show your working.

-Carotene is a naturally occurring unsaturated hydrocarbon found in carrots. A -carotene molecule contains 40 carbon atoms, has two rings, and a branched chain.

0.0200 mol of -carotene reacts with 5.28 dm³ of hydrogen gas to form a saturated hydrocarbon.

Using molecular formulae, construct a balanced equation for this reaction.

Include relevant calculations and reasoning.

Equation........