Physical

Question 1

Empirical Formula

Answer 1

The simplest whole number ratio of atoms (of each element) present in a compound

Question 2

Formation of bleach

Answer 2

Cl2 + 2NaOH –> NaClO + NaCl + H2O

Question 3

Electronegativity

Answer 3

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

Question 4

Explain why a molecule is polar

Answer 4

Net dipole
Dipoles do not cancel out
Molecule is non-symmetrical

Question 5

Isotope

Answer 5

Atoms with different number of neutrons

Question 6

Relative atomic mass

Answer 6

The weighted mean mass of an atom compared with 1/12th the mass of Carbon-12

Question 7

Relative isotopic mass

Answer 7

The weighted mean mass of an isotope compared with 1/12th the mass of Carbon-12

Question 8

Ionic lattice

Answer 8

Repeating pattern of oppositely charged ions

Question 9

Covalent bond

Answer 9

Shared pair of electrons

Question 10

Explain the different boiling points of NH3, F2 and Br2.

Answer 10

NH3 has hydrogen bonding
F2 and Br2 have London forces
Attraction is intermolecular for all 3
The London forces in Br2 are greater than in F2
Because bromine has more electrons than fluorine
hydrogen bonding in NH3 is stronger than London forces in F2

Question 11

State and explain two anomalous properties of ice caused by hydrogen bonding

Answer 11

Ice is less dense than water; The molecules in ice are held apart by hydrogen bonds

Relatively high melting point
More energy is require to overcome hydrogen bonds because hydrogen bonds are stronger then other intermolecular bonds

Question 12

State and explain two anomalous properties of ice caused by hydrogen bonding

Answer 12

Ice is less dense than water; The molecules in ice are held apart by hydrogen bonds
Ice has a relatively high melting point; Hydrogen bonds are stronger than other intermolecular
attractions or forces

Question 13

Dative Bond

Answer 13

Both electrons have been donated by one atom

Question 14

Metallic Bonding

Answer 14

attraction between the delocalised electrons and the positive ions

Question 15

Ionic Bond

Answer 15

attraction between oppositely charged ions

Question 16

Explain bond angles

Answer 16

Lone electron pairs repel more than bonded electron pairs

Question 17

State and explain the trend in atomic radius from Li to F.

Answer 17

Decreases
Nuclear charge increases
Outer electrons experience similar shielding
Greater nuclear attraction on outer electrons

Question 18

Conditions for formation of bleach

Answer 18

Cold, dilute NaOH

Question 19

Calculating Bond enthalpy

Answer 19

Bonds broken (reactants) - Bonds Made (products)

Question 20

The calculated value of ΔHc from this experiment is different from the value obtained from data books suggest reasons for the difference.

Answer 20

Heat loss
Incomplete combustion
Non-standard conditions 
Evaporation of alcohol/water
Specific heat capacity of apparatus

Question 21

Calculating enthalpy change of combustion

Answer 21

products - reactants

Question 22

State the features of a dynamic equilibrium

Answer 22

closed system
Rate of the forward reaction is equal to the rate of the reverse reaction
concentration does not change

Question 23

Explain this observation in terms of electrode potentials and equilibria. Include overall equations in your answer

Answer 23

Compare E values (which is more positive)
Equilibrium shift related to E values (More negative system shifts left, more positive system shifts right)
Full ionic equations of the system combinations

Question 24

Explain why the student uses a large excess of methanol in this experiment (rates)

Answer 24

To ensure equilibrium is to the far right

To keep methanol zero order/constant

Question 25

The enthalpy and entropy changes of a reaction both have a negative sign. Discuss how the feasibility of this reaction will change as the temperature increases

Answer 25

Reaction will become less feasible
Effect on ΔG - ΔG increases
Effect on TΔS - TΔS becomes more negative

Question 26

2NO2(g) + O3(g) —> N2O5(g) + O2(g)

Explain why this reaction has a negative entropy change.

Answer 26

products have fewer gaseous moles
becomes more ordered
fewer ways of distributing energy