Chemistry Year 10 Mock Exam

Question 1

General formula of alkanes

Answer 1

CnH2n+2 where n is the number of carbon atoms in the molecule.

Question 2

The
alkanes
form a

Answer 2

homologous series

Question 3

Like all homologous series, the alkanes:

Answer 3

have the same
general formula
differ by CH2 in
molecular formulae
from neighbouring
compounds
show a gradual variation in physical
properties
, such as their
boiling points
have similar chemical properties

Question 4

homologous series

Answer 4

A ‘family’ of organic compounds that have the same functional group and similar chemical properties.

Question 5

The alkanes are saturated hydrocarbons:

Answer 5

hydrocarbons
, because they are compounds containing hydrogen and carbon only

saturated
, because their carbon atoms are joined by C-C single bonds

Question 6

Alkanes have similiar but not identical

Answer 6

numbers of hydrogen and carbon atoms in their
molecules

boiling points
ease of
ignition

viscosity

Question 7

Alkanes and alkenes both form ————————– of hydrocarbons, but:

Answer 7

homologous series
alkanes are saturated their carbon atoms are only joined by C-C single bonds
alkenes are unsaturated they contain at least one C=C double bond

Question 8

Combustion of alkenes

Answer 8

produce one or all of soot and carbon monoxide when incompletley combusted along with water and carbon dioxide burn with a smokier, yellow (luminous) flame than alkanes
Incomplete combustion is more common with alkenes
-less energy efficient than alkanes, so do not make such good fuels
do burn completely too

Question 9

viscosity

Answer 9

(how easily it flows) increases as the chain length increases-flows less easily

Question 10

Flammability is
it increases as

Answer 10

(how easily it burns) increases as chain length decreases

Question 11

Test for unsaturation explained

Answer 11

A
if there is as an alkene there will be a positive test for unsaturation because the water will turn from colourless to orange showing that the unsaturated alkene has bonded with the bromine
if there is an alkane there will be a negative test for unsaturation because the water will remain colourless because the alkane is already saturated and thus cannot bond with the bromine water
An orange-brown solution of bromine dissolved in water, called bromine water, is used to distinguish between alkanes and alkenes:

there is no change when bromine water is mixed with an alkane
the bromine water becomes colourless when it is mixed with an alkene

Question 12

and chain length viscosity and flammabiity

Answer 12

first increases as chain length increases
second decreases

Question 13

Word thing for remembering the alkanes:

Answer 13

My Methane
Elephant Ethane
Poos Propane
Bricks Butane
Please Pentane
Help Hexane

Question 14

Alkanes and Alkenes
both undergo
complete combustion
, but only——–can undergo
addition reactions
.

Answer 14

alkenes

Question 15

Complete combustion occurs when there is an excess of ——–
The products of complete combustion of a hydrocarbon fuels are:

Answer 15

oxygen
Hydrocarbon + oxygen → carbon dioxide + water
-carbon dioxide
-water (H20)

Question 16

complete combustion uses a ———- plus oxygen to give :

Answer 16

carbon dioxide + water

Question 17

The general formula for the alkenes is :

Answer 17

CnH2n,

Question 18

alkenes contain a double

Answer 18

covalent bond

Question 19

Hydrogenation

Answer 19

Alkene + hydrogen → alkane
This is called
hydrogenation and it needs a
catalyst
For example:

Propene + hydrogen → propane

Question 20

Hydration

Answer 20

Alkene + water (steam) → alcohol
This is called
hydration
, and it needs a temperature of approximately 300°C and a catalyst.

For example:

Butene + water → butanol

Question 21

Halogenation

Answer 21

Alkene + halogen → halogenoalkane
Chlorine, bromine or iodine can be added to an alkene. These reactions are usually spontaneous. Here are some examples:

Ethene + chlorine → dichloroethane

Molecular structure of dichloroethane.
Ethene + iodine → diiodoethane

Question 22

Alcohols functional group:
and naming thing:

Answer 22

-OH
Methanol
Ethanol
Propanol
Butanol
Pentanol

Question 23

Carboxylic Acids
functional group carboxylic acids

Answer 23

The
functional group
in the carboxylic acids is the
carboxyl
group, –COOH.

Question 24

Esters functional group
are formed from an ——— and ———— A what catalyst is usually used

Answer 24

-COO-
carboxylic acid and alcohol
acid catalyst

Question 25

mass mole equation:

Answer 25

mass= mole*Mr

Question 26

gas volume calculation :

Answer 26

vol= mole * 24000 cm cubed / 24 decimeters cubed

Question 27

titration calculations:

Answer 27

mol= C*V

Question 28

percentage yield=

Answer 28

actual mass/ predicted mass
times by 100

Question 29

Covalent Molecules are

Answer 29

2 non-metals / sharing a pair of electrons

Question 30

Cl displayed formula

Answer 30

cl-cl

Question 31

Diamond structure

Answer 31

4 strong covalent bonds to each carbon atom
very hard very high bpt so
high energy to break strong covalent bonds
No delocalised electrons so it doesn’t conduct electricity

Question 32

simple molecular structures

Answer 32

held together by weak intermolecular forces
so low energy to break
low bpt

Question 33

graphite structure

Answer 33

3 strong covalent bonds to each carbon atom within layers
so very high bpt
why high energy to break strong covalent bonds
delocalised electrons between layers so conducts electricity why because delocalised electrons are free to move
weak intermolecular forces between layers so its soft
why low energy required for layers to slide over each other

Question 34

buckminster-fullerene structure

Answer 34

3 strong covalent bonds to each carbon atom within balls so its very strong so high energy needed to break string covalent bonds
delocalised electrons so conducts electricity
why because delocalised electrons are free to move
weak intermollecular forces between balls so its soft low energy required for the balls to slide over each other

Question 35

Graphene is just one layer

Answer 35

3 strong covalent bonds to each carbon atom within balls so its very strong so high energy needed to break string covalent bonds
delocalised electrons so conducts electricity
why because delocalised electrons are free to move

Question 36

Titration method

Answer 36

1. Fill the burette with hydrochloric acid using a small filter funnel. Make sure you fill the portion below the tap and remove the funnel before carrying out the titration. Take the initial reading and record it in your table.
2. Pipette 25.0cm3 of the sodium hydroxide solution into a clean 100cm3 conical flask using a graduated pipette and pipette filler. Add 5 drops of phenolphthalein indicator.
3. Titrate with 0.200mol dm-3 hydrochloric acid solution adding small amounts and swirling until the colour of the indicator changes from pink to colourless. Record the final volume in your table.
4. Empty the conical flask and rinse it with distilled water. Repeat the titration but as you approach the endpoint add the acid drop by drop and stop as soon as the solution becomes colourless.
   6.. Repeat the titration to obtain consistent results.
5. Record all your results in an appropriate table and show how you obtain a mean titre.

Question 37

Above is a Titration method, you need to make sure you know which indicator you would use and what colour change you would expect to see (according to the textbook, not what you actually see).

Answer 37

Methyl orange – red/orange in acid and yellow in alkali
Phenol phthalein – colourless in acid and pink in alkali