ST. FRANCIS SECONDARY SCHOOL

HALF YEARLY EXAMINATION – SPECIMEN PAPER

. FORM 3 CHEMISTRY TIME: 2 HOURS

Name: Total Mark from 90:

• A copy of the periodic table is provided during the exam.

• You are reminded of the necessity for good English and orderly

presentation in your answers. In calculations you are advised to show all

the steps in your working.

• Electronic Calculators may be used in any part of the examination.

• Useful Data:

• STP conditions are to be taken as 0°C and 760mmHg

Section A: Answer ALL Questions in this section. This section carries 50

marks

• This question is about Separation Techniques (Total: 7 marks)

Experimental techniques used to separate mixtures include:

• Chromatography

• Evaporation (Crystallisation)

• Sublimation

• Filtration

• Distillation

• Fractional Distillation

• Separating Funnel

Give the letter of the most suitable process for:

• Obtaining crystals of sodium chloride from sodium chloride

solution…………..

• Separating a solid precipitate from the liquid in which it has been

produced………….

• The separation of a solute and a solvent while keeping both the solute and

the solvent…………..

• Separating two immiscible liquids such as oil and water…………….......

• Finding what coloured substances are present in flower

petals…………………

• Separating iodine from solid carbon………………

• Separating two miscible liquids with different boiling points such as

alcohol and water…………….

(1 mark each)

• This question is about Atomic Structure and the Periodic table

(Total: 19 marks)

• Use the periodic table to give the name and symbol of:

Name Symbol

•

• A Non-Metal which is not a Halogen

• A Transition Metal

• An Inert Gas

• An Alkaline Earth Metal

(4 marks)

• Give the electronic configurations of:

• Argon

• Sodium

• Chlorine (3 marks)

• There are three different atoms of Magnesium, namely;

Complete the following statements:

• These atoms are all of magnesium.

• There are neutrons in an atom of . (2 marks)

• Complete the following table:

Mass Number

Atomic Number

Number of Protons

Number of Electrons

Number of Neutrons

(10 marks)

• This question is about Kinetic Theory and States of Matter (Total: 11

marks)

• What happens to the molecules of a solid when the solid melts to form a

liquid?

(2 marks)

• What happens to the molecules of a liquid when the liquid boils to form

a gas?

(2 marks)

• A tube

is set up, as shown in the diagram below, with ammonia gas given

off at A and hydrogen chloride gas given off from the solution at B. The

gases move through the air in the tube and meet at point X, where a

white solid forms.

• State the name of the process occurring when the molecules of each gas

mix with, and move past, air molecules.

(1 marks)

• Give the name of the white solid formed at X.

(1 marks)

• Use the diagram to compare the rates at which ammonia and hydrogen

chloride gases move.

• marks)

• A gas occupies a volume of 400cm3 at a temperature of 30

0C and a

pressure of 600mmHg. Calculate the volume occupied by the gas at

STP.

(3 marks)

• This question is about Bonding (Total: 13 marks)

• State the formula of the compound formed by combination of

magnesium and oxygen only

(1 Marks)

• The compound in question 4.a. is ionic. Explain why you expect this.

(2 Marks)

• Carbon dioxide, CO2, is a covalent compound. In the space on the next

page, draw a diagram (showing outer electrons only) of the carbon

dioxide molecule. Use x for the electrons of carbon and • for the

electrons of the oxygen.

(4 marks)

• Beryllium Chloride, BeCl2, is an ionic compound. In the space below

draw diagrams (showing ALL electrons) of the Beryllium ion and the

Chloride ion.

A Beryllium Ion A Chloride Ion

(4 marks)

• The Table below shows some properties of substances W and X.

Substance Melting Point (°C) Solubility in Water

Ability to conduct

electric current when

molten

W 44 Insoluble Poor

X 808 Soluble Good

• Select using the letters W and X, the substance which is most likely to

be

• a simple molecular, covalent substance…………….

• an ionic solid…………………..

• marks)

Section B: Answer TWO Questions from this section on separate sheets.

Each Question carries 20 marks.

• This question is about Separation techniques (Total: 20 marks)

Mixtures of substances can be separated by filtration, distillation and paper

chromatography. Choosing a suitable named example and including a fully

labelled diagram of the apparatus used describe briefly how:

• Filtration can be used to separate an insoluble solid from water.

(6 marks)

• Distillation can be used to recover a solvent from a solute solution

(7 marks)

• Paper chromatography can be used to separate a mixture of coloured,

soluble solids.

(7 marks)

• This question is about Bonding (Total: 20 marks)

• Explain the difference between ionic bonding and covalent bonding in

terms of electrons.

(3 marks)

• Give an example of an ionic compound and draw a dot and cross

diagram for the ionic compound showing outer electrons only. Give at

least TWO properties of ionic compounds.

(7 marks)

• Give an example of a simple covalent molecule and draw a dot and

cross diagram for the simple covalent molecule showing outer electrons

only. Give at least TWO properties of simple covalent molecules.

(7 marks)

• Give an example of a compound which undergoes sublimation and

explain what happens to the compound during sublimation.

(3 marks)

• This question is about Atomic Structure and the Periodic table

(Total: 20 marks)

• Atoms are neutral in spite of being made up of positive (protons) and

negative (electrons) particles. Explain this statement.

(2 marks)

• Define the term isotopes and explain why isotopes have the same

chemical properties.

(3 marks)

• Calculate the Relative Atomic Mass of Magnesium given that the

natural abundance of the isotopes of Magnesium are as follows:

• 24Mg – 78.99%

• 25Mg – 10.00%

• 26Mg – 11.01%

Give your answer to 2 decimal places (3

marks)

NOT FINISHED YET, TURN OVER THE PAGE!

• Explain the following statements:

• On-going across a period from left to right of the periodic table the

Atomic Radius decrease.

(3 marks)

• Nobel Gases are also called Inert Gases since they do not form any

compounds and therefore they do not react.

(3 marks)

• On-going down Group 1 Metals the Reactivity increase.

(3 marks)

• Calculate the relative molecular mass of the following compounds:

• BaCl2

• (NH4)2SO4

• Na2CO3

(3

marks)

THE END – GOOD LUCK! ;)