Module 2 - Foundations in Chemistry - Exam Questions

Question 1

Define relative isotopic mass (2)

Answer 1

Mass of the isotope compared to 1/12th of the mass of a carbon 12

Question 2

Define isotopes (1)

Answer 2

Atoms with the same number of protons but a different number of neutrons

Question 3

Explain why isotopes have the same chemical properties (1)

Answer 3

Same number of electrons in the outer shell

Question 4

Define relative atomic mass (3)

Answer 4

The weighted mean mass of an atom relative to 1/12th the mass of one atom of carbon 12

Question 5

How could the fraction of the isotopes of carbon be found experimentally? (1)

Answer 5

Mass spectrometry

Question 6

Explain what is meant by a salt (1)

Answer 6

When the H+ in an acid is replaced by a metal ion

Question 7

What term is given to the .n H2O part of a formula? (1)

Answer 7

Waters of crystallisation

Question 8

What calcium compound is formed when calcium oxide reacts with water? (1)

Answer 8

Calcium hydroxide

Question 9

What calcium compound is formed when calcium oxide reacts with nitric acid? (1)

Answer 9

Calcium nitrate

Question 10

How do old samples of magnesium oxide become contaminated with magnesium carbonate? (1)

Answer 10

MgO has reacted with CO2

Question 11

A student adds an excess of HCl to magnesium oxide and magnesium carbonate, state two observations that would be made (2)

Answer 11

Solid dissolves

Effervescence

Question 12

Define an acid (1)

Answer 12

A proton donor

Question 13

How can CaCO3 be used to combat excess stomach acid? Use an equation (2)

Answer 13

CaCO3 neutralises HCl

CaCO3 + 2HCl -> CaCl2 + H2O + CO2

Question 14

State an important use of ammonium sulphate (1)

Answer 14

Fertiliser

Question 15

State a large-scale use of ammonia (1)

Answer 15

Manufacture of explosives

Question 16

Explain, in terms of electrons, what is meant by oxidation (1)

Answer 16

Loss of electrons

Question 17

What is meant by the term mole? (1)

Answer 17

Amount of substance that has the same number of particles as there are atoms in 12g of carbon 12

Question 18

What is a common use of NaClO? (1)

Answer 18

Bleach

Question 19

After Ca has fully reacted with HCl, upon adding more Ca, a reaction still takes place, why? (3)

Answer 19

Ca has reacted with water

Ca + 2H2O -> Ca(OH)2 + H2

Question 20

Explain what is meant by molecular formula (1)

Answer 20

Number and type of atoms making up a molecule

Question 21

What is meant by ionic bonding? (1)

Answer 21

Electrostatic attraction between oppositely charged ions

Question 22

Predict the bond angle in an F2O molecule and explain (3)

Answer 22

104.5
There are 2 bonded pairs and 2 lone pairs
Lone pairs repel more than bonded pairs

Question 23

Describe and explain two anomalous properties of water from hydrogen bonding (4)

Answer 23

Liquid H2O is more dense than solid
Ice has open lattice
H2O has a relatively high boiling point
Hydrogen bonds need to be broken

Question 24

What is meant by a covalent bond? (1)

Answer 24

A shared pair of electrons

Question 25

Name the shape of the ammonia molecule and why ammonia has this shape and a bond angle of 107° (3)

Answer 25

Pyramidal There are 3 bonded pairs and 1 lone pair Lone pairs repel more than bonded pairs

Question 26

Why does ammonium chloride not conduct electricity when solid but does when dissolved in water? (2)

Answer 26

Ions cannot move in a solid | Ions can move in solution

Question 27

Why does H2S have a much lower boiling point than H2O? (2)

Answer 27

No hydrogen bonding | Weaker intermolecular forces

Question 28

What is meant by hydrogen bonding? (1)

Answer 28

Interaction between lone pair of F, N or O and a H in a neighbouring molecule

Question 29

Explain electronegativity (2)

Answer 29

Attraction of an atom for electrons in a covalent bond

Question 30

Why do O-H and N-H bonds have dipoles? (1)

Answer 30

Oxygen and nitrogen are more electronegative than hydrogen

Question 31

Why does a water molecule have a different shape to a carbon dioxide molecule? (2)

Answer 31

Electron pairs repel Oxygen in water has 2 bonds and 2 lone pairs Carbon in CO2 has 2 double bonds

Question 32

Why is water a polar molecule, but CO2 is not?

Answer 32

CO2 is symmetrical | In CO2, dipoles cancel

Question 33

State the ON's H202

Answer 33

``` H = -2 O = -2 ```

Question 34

State the ON's for Ca(ClO4)2

Answer 34

Ca= +2 Cl= +7 O=-2

Question 35

State the ON's for BrF5

Answer 35

Br=+5 | F=-1

Question 36

State the ON's for BrO3

Answer 36

Br=+6 | O=-2

Question 37

State the ON's for CaO

Answer 37

Ca=+2 | O=-2

Question 38

State the ON's for CuI

Answer 38

Cu=+1 | I=-1

Question 39

State the ON's for FeBr3

Answer 39

Fe=+3 | Br=-1

Question 40

State the ON's for NH4Cl

Answer 40

N=-3 H=+1 Cl=-1

Question 41

State the ON's for KClO3

Answer 41

K=+1 Cl=+5 O=-2

Question 42

State the ON's for H2P2O7

Answer 42

H=+1 P=+6 O=-2

Question 43

State the ON's for (NO2)-

Answer 43

N=+3 | O=-2

Question 44

State the ON's for ZnH2

Answer 44

Zn=+2 | H=-1

Question 45

State the ON's for KCl

Answer 45

K=+1 | Cl=-1

Question 46

State the ON's for O3

Answer 46

0

Question 47

The element strontium forms a nitrate, Sr(NO3)2, which decomposes on heating as shown below. 2Sr(NO3)2(s) → 2SrO(s) + 4NO2(g) + O2(g) (i) Using oxidation numbers, explain why the reaction involves both oxidation and reduction.

Answer 47

N changes from +5 in 2Sr(NO3)2 to +4 in 4NO2, therefore its Reduced. O changes from -2 in 2Sr(NO3)2 to 0 in O2, therefore its Oxidised.