Organic Chemistry

Question 1

(1) Which of the following is the formula for a molecule of butane?

Answer 1

C4H10

Question 2

(2) Draw the structure of a molecule of propene, showing all covalent bonds.

Answer 2

one C=C in a molecule with three
consecutive carbon atoms (1)
rest of structure correct, ignore
bond angles, conditional on first
marking point(1)

Question 3

(1) Ethanol is converted into ethanoic acid. In this reaction, ethanol is

Answer 3

oxidised

Question 4

(2) Describe what you would see when solid sodium carbonate is added to dilute
ethanoic acid.

Answer 4

effervescence / fizzing /
bubbles of gas (1)
• solid {disappears/clears}
/(colourless)solution formed
(1)

Question 5

(2) ) When ethanoic acid reacts with ethanol, one of the products is the ester, ethyl
ethanoate.
CH3COOH + C2H5OH → ……………………. + …………………

Answer 5

CH3COOC2H5/CH3COOCH2CH3 /
CH3CO2C2H5 / CH3CO2CH2CH3 /
C2H5O2CCH3 / CH3CH2OOCCH3 (1)
H2O (1)

Question 6

(2) Ethanol can be produced by reacting ethene with steam.

Write the balanced equation for this reaction.

Answer 6

C2H+H2O= C2H5OH

Question 7

(2) Describe how ethanol can be produced from sugar by fermentation.

Answer 7

dissolve sugar in solutio (1)
add yeast (1)
warm temp to range within 15 to 40 degree celcius (1)
anaerobic oxygen can enter the apparatus (1)

Question 8

(3) A country has large amounts of available fertile land.
It has no reserves of crude oil.
It is not a wealthy country.
Explain why this country produces the ethanol it needs by fermentation rather
than from ethene

Answer 8

Marking point 1 – sugar- one from
• sugar obtained from {plants
/crops/specific crop} (1)
• (plenty of) land available to grow
{plants /crops/specific crop} (for
fermentation)(1)
Marking point 2 - ethene
• ethene obtained from {crude oil /
fractional distillation /cracking}
(1)
Marking point 3 – cost/energy – one
from
• cannot afford to buy crude oil (1)
• crude oil is too expensive (1)
• more expensive to
{use/buy/produce} ethene (1)
• cheaper to use fermentation (1)

Question 9

(2) Ethanol is a member of the homologous series of alcohols.
The first three members of the series are
methanol CH3OH
ethanol C2H5OH
propanol C3H7OH

Use the formulae of these molecules to explain why these alcohols are members
of the same homologous series.

Answer 9

formulae differ by CH2
• same general formula
• all have {OH/hydroxyl group}

Question 10

(1) The conditions used for fermentation are

Answer 10

add yeast, temperature of
35o
C

Question 11

(2) Ethanol, C2H5OH, is also produced by the reaction of ethene with steam.
Write the balanced equation for this reaction.

Answer 11

C2H4 (1) + H2O (1) → C2H5OH

Question 12

(2) Describe what is meant by an homologous series.

Answer 12

same general formula (1)
 same functional group (1)
 (consecutive) compounds
differ by CH2 (1)
 gradual variation in physical
properties (1)
 {similar / same} chemical
{properties / reactions} (1)

Question 13

(1) Draw the structure of a molecule of methanol, CH3

OH.

Answer 13

allow –OH
allow correct dot and cross
diagram

Question 14

(1) State the type of reaction that occurs when ethanol changes into ethanoic acid.

Answer 14

oxidation

Question 15

(2) Describe what you would see when a piece of magnesium ribbon is added to
dilute ethanoic acid.

Answer 15

effervescence/fizzing/bubbling
(1)
 solid disappears (1)
 colourless solution (1)

Question 16

(1) In hydrogenation of a liquid oil

Answer 16

the liquid oil is changed into

a solid

Question 17

(1) Which of the following would be a suitable alkali to use in the production of soaps?

Answer 17

sodium hydroxide

Question 18

(2) Explain how soap anions remove grease marks from clothes during washing
with water.

Answer 18

tail / {hydrophobic /
hydrocarbon } end into grease
(1)
 head / {anion / hydrophilic}
end into water (1)
 allows grease to mix with
water when surrounded by
soap (anions) / grease is
surrounded by soap (1)
 surface tension lowered (1)

Question 19

(1) Give the name of the carboxylic acid that has three carbon atoms in each molecule.

Answer 19

propanoic (acid)

Question 20

(2) When ethanoic acid, CH3COOH, reacts with ethanol, C2H5OH, ethyl ethanoate
is one of the products formed.
Write the balanced equation for the reaction.

Answer 20

CH3COOH + C2H5OH 

CH3COOC2H5 (1) + H2O (1)

Question 21

(1) Polyesters are used to make plastic bottles.

State another use of polyesters.

Answer 21

(making) fibres/fleece/clothing/
fabrics/bedding/computer mouse
mats/yarns/ropes/safety
belts/filters/insulating tape/wood
finishes/(plastic) carrier bags

Question 22

(1) HCl(aq) + NaOH(aq) ĺ NaCl(……..) + H2

O(……..)

Answer 22

aq, l

Question 23

(1) Which of the following would be a suitable alkali to use in the production of soaps?

Answer 23

sodium hydroxide

Question 24

(1) Give the molecular formula of ethyl ethanoate

Answer 24

C4H8O2

Question 25

(2) Write the word equation for the reaction of ethanol with another compound to form ethyl ethanoate and another product.

Answer 25

ethanol + ethanoic acid → ethyl ethanoate + water (2)

Question 26

(1) Exposure to the vapour of ethyl ethanoate can cause you to feel dizzy or to faint Suggest why, despite this hazard, it is still safe to use ethyl ethanoate in sweets.

Answer 26

``` no vapour/ little vapour (given off) / it is not a gas / it is a solid (not vapour) small amount/ concentration in sweets ```

Question 27

(1) One of these oils is boiled with concentrated sodium hydroxide solution. The mixture is poured into concentrated sodium chloride solution. A white solid is formed. What type of substance is the white solid?

Answer 27

soap

Question 28

(2) The white solid is formed in a mixture with a solution of other substances. Describe how a pure sample of the white solid can be obtained from this mixture.

Answer 28

filter / decant off water (1)  (then) wash/rinse (1)

Question 29

(1) Liquid oils can be converted into solid fats by hydrogenation. In this reaction

Answer 29

unsaturated molecules in the liquid oil become saturated

Question 30

(2) Ethanol is produced by the fermentation of glucose. Yeast is needed for the fermentation reaction. State two other conditions for fermentation.

Answer 30

``` dissolve the sugar/aqueous solution (1)  warm/ 25-40°C (1)  in absence of air / no oxygen/ anaerobic / attach airlock (1)  pH neutral / slightly acidic /4-7  sterile conditions ```

Question 31

(1) A dilute solution of ethanol can be converted to a concentrated solution of ethanol by

Answer 31

fractional distillation

Question 32

(2) Write the balanced equation for the fermentation of glucose, C6 H12O6 .

Answer 32

C6H12O6 → 2 C2H5OH + 2 CO2 | 2

Question 33

(2) In industry, ethene is converted to ethanol. | State two conditions for this reaction.

Answer 33

``` (reacts with) steam (1)  catalyst/phosphoric acid (1)  high temperature / 200°C - 4500C (1)  high pressure/ 50-100 atm (1) ```

Question 34

(3) A country has large reserves of crude oil. It is a relatively wealthy country with a large population but it has only a small amount of fertile land. Explain why the country would prefer to produce its ethanol from ethene rather than by fermentation.

Answer 34

LAND: country needs land for: farming / food / crops / homes /not enough land to grow sugar crop for fermentation (1) OIL SUPPLY: (reliable supply of) crude oil for ethene (1) SPEED: fermentation slow/batch; hydration continuous/ fast (1) PURITY: hydration makes {pure(r) ethanol / high concentration} (1) ATOM ECONOMY: higher atom economy for ethene process (1)

Question 35

(2) Draw the structure of a molecule of propene, showing all bonds.

Answer 35

any 3 carbon molecule and one C=C (1) | fully correct molecule with all bonds (2)