Chemistry Paper 2 Topic 7

Question 1

What two ELEMENTS do hydrocarbons contain?

Answer 1

The two elements hydrocarbons contain are HYDROGEN and CARBON atoms.

Question 2

What is the general FORMULA for ALKANES?

Answer 2

CnH2n+2

Question 3

What two WASTE PRODUCTS form from the COMPLETE combustion of hydrocarbons?

Answer 3

The COMPLETE COMBUSTION of any hydrocarbon in oxygen releases lots of energy.
The only waste products are CARBON DIOXIDE and WATER VAPOUR.

Question 4

List some PROPERTIES of a SHORTER carbon chain.

Answer 4

The SHORTER the carbon chain the LESS VISCOUS it is.

Hydrocarbons with SHORTER carbon chains are MORE VOLATILE. i.e. they have LOWER BOILING POINTS.

Also, the SHORTER the carbon chain, the MORE FLAMMABLE (easier to ignite) the hydrocarbon is.

Question 5

Name the FIRST FOUR alkanes.

Answer 5

The FIRST FOUR alkanes are METHANE, ETHANE, PROPANE, and BUTANE.

Question 6

Are alkanes SATURATED or UNSATURATED?

Answer 6

Alkanes are SATURATED COMPOUNDS - each carbon atom forms four single covalent bonds.

Question 7

What process is performed to separate CRUDE OIL into different HYDROCARBONS?

Answer 7

CRUDE OIL is a MIXTURE of LOTS OF DIFFERENT HYDROCARBONS, most of which are ALKANES.
The different compounds in CRUDE OIL are SEPARATED by FRACTIONAL DISTILLATION.

Question 8

Why are SHORT-CHAINED HYDROCARBONS in such HIGH DEMAND?

Answer 8

SHORT-CHAINED HYDROCARBONS are flammable so they make good fuels and are in HIGH DEMAND.

However, LONG-CHAINED HYDROCARBONS form VERY VISCOUS LIQUIDS like TAR which aren’t all that useful.

Question 9

What process is used to SPLIT up LONG-CHAINED HYDROCARBONS into SHORTER-CHAINED HYDROCARBONS?

Answer 9

A lot of the LONGER alkane molecules produced from FRACTIONAL DISTILLATION are TURNED into SMALLER, MORE USEFUL ones by a process called CRACKING

Question 10

Name two DIFFERENCES between ALKANES and ALKENES.

Answer 10

ALKENES have a DOUBLE CARBON-CARBON BOND.

This means ALKENES are UNSATURATED.

Question 11

Why do ALKENES burn in the air with a SMOKY FLAME?

Answer 11

There is NOT enough OXYGEN in the air, so when you burn alkenes they undergo INCOMPLETE COMBUSTION.

Question 12

What is used to test for ALKENES?

Answer 12

The addition of BROMINE WATER is used to test for ALKENES.

If BROMINE WATER is added to an UNSATURATED COMPOUND like an ALKENE the BROMINE will add ACROSS the double bond, making a COLOURLESS dibromo-compound.
So the BROMINE WATER is DECOLOURISED.

Question 13

What type of compounds are used as the MONOMERS to make ADDITION POLYMERS?

Answer 13

The MONOMERS that make up ADDITION POLYMERS are often ALKENES.

Question 14

What is the general FORMULA for ALCOHOLS?

Answer 14

Cn H2n+1-OH

Question 15

Give the NAMES and FORMULAS of the FIRST FOUR ALCOHOLS.

Answer 15

METHANOL - CH3-OH

ETHANOL - C2 H5-OH

PROPANOL - C3 H7-OH

BUTANOL - C4 H9-OH

Question 16

Name the GAS that is PRODUCED when ETHANOL reacts with SODIUM

Answer 16

One of the PRODUCTS of ETHANOL and SODIUM is HYDROGEN.

Question 17

Name the PROCESS that CONVERTS SUGAR to ETHANOL using YEAST

Answer 17

FERMENTATION uses an enzyme in YEAST to convert SUGARS into ETHANOL.

Question 18

Why are CARBOXYLIC ACIDS considered to be WEAK ACIDS?

Answer 18

When they dissolve, they IONISE and RELEASE H+ IONS resulting in an acidic solution.
But, because they DON’T IONISE COMPLETELY (not all the acid molecules release their H+ ions), they just form WEAK acidic solutions.

Question 19

Give the general WORD EQUATION for the reaction of an ALCOHOL and a CARBOXYLIC ACID.

Answer 19

ALCOHOL + CARBOXYLIC ACID —> ESTER + WATER

Question 20

How many DIFFERENT PRODUCTS are there in a CONDENSATION POLYMERISATION reaction?

Answer 20

Two types of PRODUCTS - the POLYMER and a SMALL MOLECULE (e.g. water)