FC 9-26

Question 1

Define electronegativity.

Answer 1

The ability of an atom to attract the bonding electrons in a covalent bond.

Question 2

What is the oxidation state of elements in elemental state?

Answer 2

0.

Question 3

What is the oxidation state of a simple ion?

Answer 3

The charge on the ion.

Question 4

Colour of Chlorine in aqueous solution.

Answer 4

Pale yellow.

Question 5

Colour of Bromine in aqueous solution.

Answer 5

Orange.

Question 6

Colour of Iodine in aqueous solution.

Answer 6

Brown.

Question 7

Colour of Chlorine in Cyclohexane.

Answer 7

Pale yellow.

Question 8

Colour of Bromine in Cyclohexane.

Answer 8

Orange.

Question 9

Colour of Iodine in Cyclohexane.

Answer 9

Purple.

Question 10

Aqueous Chlorine reacts with water in a disproportionation reaction to form what?

Answer 10

HCl and HOCl (Chloric acid).

Question 11

Chlorine reacts with cold, dilute, aqueous NaOH in a disproportionation reaction to form what?

Answer 11

NaCl, NaClO (Sodium Chlorate) and Water.

Question 12

How would you test for the Carbonate ion?

Answer 12

Add dilute nitric acid, and check for effervescence.

Question 13

How would you test for the Sulphate ion?

Answer 13

Add barium nitrate, and check for a white precipitate.

Question 14

How would you test for the ammonium ion?

Answer 14

Warm your unknown solution, and add aqueous NaOH. Check for ammonia gas being released using damp red litmus paper. It will turn blue if ion is present.

Question 15

Define homologous series.

Answer 15

A series of compounds that have the same general formula and functional group, and which successive members differ by an extra CH2 unit.

Question 16

Define isomers.

Answer 16

Different compounds with the same molecular formula.

Question 17

Define structural isomers.

Answer 17

Compounds with the same molecular formula but different structural formula.

Question 18

By what mechanism do alkanes and halogens react?

Answer 18

Radical substitution.

Question 19

Define stereoisomers.

Answer 19

Isomers with the same structural formula but a different arrangement in space.

Question 20

How can you form an alkene from an alcohol?

Answer 20

Dehydrate the alcohol under heating and in the presence of a sulphuric acid catalyst.

Question 21

How can you form alkanes from alkenes?

Answer 21

React the alkene with hydrogen under heating, in the presence of a nickel catalyst.

Question 22

How can you form haloalkanes from alkenes?

Answer 22

By reacting the alkene with a GASEOUS hydrogen-halide, or just with a halogen molecule like chlorine. These are electrophilic addition reactions. The reaction can be used as a test for unsaturation, as (orange) bromine water will go colourless if it reacts.

Question 23

How can you form an alcohol from an alkene?

Answer 23

By reacting the alkene with steam and a phosphoric acid catalyst. This is called hydration.

Question 24

Define electrophile.

Answer 24

An electron pair acceptor.

Question 25

What determines the major product of an addition reaction?

Answer 25

The stability of the carbocation intermediate.

Question 26

What can we do with waste polymers?

Answer 26

Recycle them, combust them, or use them as feedstock for the production of new plastics and other organic compounds.

Question 27

Define nucleophile.

Answer 27

An electron pair donor.

Question 28

What are the standard conditions?

Answer 28

1 atmosphere of pressure (100kPa) and 25^C.

Question 29

Define enthalpy change of a reaction.

Answer 29

The enthalpy change when the number of moles shown in the equation react to form the products.

Question 30

Define standard enthalpy change.

Answer 30

Enthalpy change of a reaction where all substances are in their standard state and standard conditions are used.

Question 31

Define enthalpy change of combustion.

Answer 31

The enthalpy change when 1 mole of substance is completely burned in Oxygen.

Question 32

Define enthalpy change of formation.

Answer 32

The enthalpy change when 1 mole of substance is formed from its elements.

Question 33

Define enthalpy change of neutralisation.

Answer 33

The enthalpy change when 1 mole of water is formed from a neutralisation reaction.

Question 34

State Hess’ law.

Answer 34

The enthalpy change of a reaction is independent from the route taken by the reaction, provided the conditions don’t change.

Question 35

Why are some bond enthalpy values averages?

Answer 35

Because some bonds appear in many different compounds, so their bond enthalpy has to be calculated from a range of different compounds.

Question 36

Define bond enthalpy.

Answer 36

The enthalpy change when 1 mole of bonds are broken, in molecules in gaseous state.

Question 37

Why are enthalpy changes calculated from average bond enthalpies not 100% accurate?

Answer 37

3 reasons:
• Because enthalpies are average values.
• Because bond enthalpies aren’t calculated under standard conditions.
• Because bond enthalpies only predict gas phase changes.

Question 38

What is the name of the oxidising agent, used to oxidise alcohols?

Answer 38

Warm, aqueous, acidic potassium dichromate.

Question 39

What is the colour change when an alcohol is oxidised?

Answer 39

Orange to green, as the orange dichromate ions are reduced to green Cr 3+ ions.

Question 40

State le Chatelier’s principle.

Answer 40

When one of the conditions affecting the position of a dynamic equilibrium is changed, the position of the equilibrium will shift in the direction that opposes the change.