Unit 6

Question 1

1. Which elements are present in alkanes?

Answer 1

Carbon and hydrogen

Question 2

2. Name the first 8 alkanes and write formula for them..

Answer 2

Methane, CH4; Ethane C2H6 ; Propane C3H8 ; Butane C4H10; Pentane C5H12; Hexane C6H14; Heptane C7H16; Octane C8H18

Question 3

8. When an alkane is fully burnt in oxygen what are the 2 products formed?

Answer 3

Carbon dioxide and water

Question 4

14. Name and give the formula for the first 8 members of the cycloalkanes.

Answer 4

Cyclopropane C3H6, Cyclobutane C4H8, Cyclopentane C5H10, Cyclohexane C6H12, Cycloheptane C7H14, Cycloctane C8H16, Cyclononane C9H18, Cyclodecane C10 H20

Question 4

3. What is the general formula for the alkanes?

Answer 4

Cn H2n 2+

Question 4

Name the substances that would form if there is incomplete combustion of any alkane
e.g. methane

Answer 4

Carbon monoxide / or even carbon and water

Question 5

4. What type of bonding do alkanes have?

Answer 5

Covalent

Question 5

6. As the length of the carbon chain increases what happens to the melting and boiling points of the alkanes?

Answer 5

As the C chain length increases the boiling point increases
As the size of the molecule increases, the intermolecular forces increase

Question 5

What does a substance react with during combustion?

Answer 5

oxygen

Question 6

9. Be able to write a balanced equation to show the reaction for the complete combustion of any alkane.

e.g. Write the equation to show the combustion of methane.

Answer 6

CH4 + 2O2 → CO2 + 2H2O

Question 6

5. Given the name of an alkane, be able to write the molecular formula, structural formula and shortened structural formula.
   Write the molecular formula for propane.

Draw the full structural formula for propane

Draw the shortened structural formula for propane.

Answer 6

i. C3 H8

ii. H-C-C-C-H

iii. CH3CH2CH3

Question 7

Be able to draw a full structural formula for any branched chain alkane from the name.

2 - methyl butane
2, 2 - dimethyl pentane

Answer 7

https://docs.google.com/document/d/1AlPRvzOWtHYYHg3e2lVM_tpFbbVBWmTWzJXXJ5a4Iqc/edit?pli=1&tab=t.0

Question 7

i) What is meant by the term isomer?

ii) Name 3 things that are different for isomers.

Answer 7

i) Same molecular formula but different structural formula

ii) Structure, name, properties

Question 8

13. Name the elements present in cycloalkanes.

Answer 8

Carbon, hydrogen

Question 9

15. What is the general formula for the cycloalkanes?

Answer 9

CnH2n

Question 10

16. Be able to write the molecular formula and full structural formula for any named cycloalkane.

Answer 10

C4H8

Question 11

What are the products of combustion of cycloalkanes?

Answer 11

Carbon dioxide and water

Question 12

What type of carbon to carbon bond do alkenes have in their structure?

Answer 12

Carbon/carbon double bond

Question 13

Compounds with at least one carbon to carbon double bond are called

Answer 13

unsaturated

Question 13

Be able to draw and identify isomers of alkenes and cycloalkanes.
Eg. Draw the full structural formula and name the isomers of

i) Propene

ii) Butene

Answer 13

i. Prop-1-ene

i. Cyclopropane

ii. But-1-ene

ii. But-2-ene

ii. Cyclobutane

Question 14

i) What would you use to test a compound to see if it contained a carbon to carbon double bond.

ii) What would you expect to observe if the compound did have a C=C present?

iii) Write an equation to show the reaction between prop-1-ene and bromine

Answer 14

i. Bromine water

ii. Goes from orange to colourless

Question 15

Write an equation to show how ethene will react with hydrogen to make ethane.

Answer 15

C2H4 + H2 → C2H6

Question 16

What is the name given to this type of reaction?

Answer 16

Hydrogenation