Module 3

Question 1

Define first ionisation energy

Answer 1

the energy required to remove one electron from each atom in one mole of gaseous atoms of an element

Question 2

Which factors affect ionisation energy across a Period?

Answer 2

Atomic Radius Decreases
Nuclear Charge Increases
Electron Shielding Remains Similar
(Greater Charge Density)
First Ionisation Energy Increases

Question 3

Which factors affect ionisation energy down a Group?

Answer 3

Atomic Radius Increases
Nuclear Attraction Decreases
Electron Shielding Increases
First Ionisation Energy Decreases

Question 4

Describe Metallic Bonding

Answer 4

The electrostatic attraction between positive metal ions and a sea of delocalised electrons

Question 5

What is the pattern in melting points across the period table?

Answer 5

It increases from groups 1 to 14 (giant structures) and then decreases from groups 15 to 18 (simple molecules with IM-forces) ((After Si))

Question 6

Why does the reactivity of group 2 elements increase down the group?

Answer 6

Group 2 elements react by losing electrons, further down the group the attraction between the outer-electron and the nucleus decreases

Question 7

Describe the trend in the solubility of group 2 hydroxides?

Answer 7

As you descend the group, solubility of the group 2 hydroxide increases and hence, pH increases also

Question 8

How does the reactivity of the Halogens change down the group?

Answer 8

It decreases, because the atomic radius is increasing and so is the shielding

Question 9

What is a disproportionation reaction?

Answer 9

One where the same species is both oxidised and reduced

Question 10

State a concern associated with putting chloride ions in the water to sterilise it

Answer 10

It might react with alkanes, to form carcinogenic haloalkanes

Question 11

What is the correct order to carry out the qualitative negative ion tests?

Answer 11

1) Carbonate (add nitric acid, makes carbon dioxide)
2) Sulphate (add barium nitrate, makes a white ppt)
3) Halide (add silver nitrate, makes coloured ppts)
(‘4’) add ammonia to coloured ppts, only iodine will not dissolve)

Question 12

Define enthalpy change of reaction

Answer 12

the enthalpy change that accompanies a reaction in the molar quantities in the equation

Question 13

Define enthalpy change of formation

Answer 13

the enthalpy change that accompanies the formation of one mole of a compound from its elements

Question 14

Define enthalpy change of combustion

Answer 14

the enthalpy change that takes place when one mole of a substance reacts completely with oxygen

Question 15

Define enthalpy change of neutralisation

Answer 15

the enthalpy change that accompanies the reaction of an acid by a base to produce one mole of water

Question 16

What is the equation for energy change (involving specific heat capacity)?

Answer 16

q=mc Δt

Question 17

What can cause inaccuracies in the experimental enthalpy change value compared to the standard one?

Answer 17

It was measured in non-standard conditions
Incomplete combustion occurred
Heat was lost (transferred) to the surroundings

Question 18

What is the bond enthalpy of a bond?

Answer 18

The energy required to break one mole of the bond in its gaseous state

Question 19

What factors can affect the rate of a reaction?

Answer 19

Concentration / Pressure
Temperature
Use of a catalyst
Surface area (if solid)

Question 20

What defines whether or not a collision is effective in a reaction?

Answer 20

If it has or not collided in the correct orientation, and with enough energy, to actually react

Question 21

What are the key features of catalysts?

Answer 21

They lower activation energy, without undergoing any permanent change themselves (always regenerated)

Question 22

What is the difference between Homogenous and Heterogeneous catalysts?

Answer 22

Homogenous catalysts are in the same state as the reactants, and often form intermediates. Heterogeneous catalysts are in a different state to the reactants and work by adsorption and desorption

Question 23

What is autocatalysis?

Answer 23

When the product of a reaction acts as a catalyst for that reaction

Question 24

What does the area under the curve resemble in the Boltzmann Distribution?

Answer 24

The total number of particles

Question 25

What effect does increasing temperature have on the Boltzmann curve?

Answer 25

It stretches the curve horizontally, lowering the maximum point, but the total area remains the same

Question 26

What is Le Chatelier’s Principle?

Answer 26

When a system is in a dynamic equilibrium and is subjected to an external change, the system will readjust itself to counteract the change

Question 27

In a dynamic equilibrium, what effect will increasing the temperature have?

Answer 27

It will encourage the endothermic direction, to oppose the increase

Question 28

In a dynamic equilibrium, what effect will increasing the pressure have?

Answer 28

It will encourage the reaction that produces fewer moles of gas, to oppose the increase