Periodic Table And Energy

Question 1

How are elements arranged in a periodic table

Answer 1

They’re arranged in the order of increasing atomic numbers

Question 2

What is meant by periodicity

Answer 2

Repeating trends in chemical and physical properties

Question 3

Define first ionisation energy

Answer 3

The energy required to remove one electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions

Question 4

What are the factors that effect ionisation energy

Answer 4

Atomic radius
Nuclear charge
Electron shielding of screening

Question 5

Why does first ionisation energy decrease between group 2 to 3

Answer 5

In group 3 outermost electrons are in p orbital whereas in group 2 they’re in s orbital so electrons are easier to remove

Question 6

Does first ionisation increase or decrease between the end of one period and the start of the next

Answer 6

Decrease because
Increase in atomic radius
Increase in electron shielding

Question 7

Does first ionisation Increase or decrease down a group

Answer 7

Decrease because
Shielding increases
Atomic radius increases

Question 8

What’s the most reactive metal of group 2

Answer 8

Barium

Question 9

3 physical properties of group 2 metals

Answer 9

High melting and boiling points
Low density metals
Form colorless compounds

Question 10

Does reactivity increase or decrease down group 2

Answer 10

Increases- electrons are lost more easily because larger atomic radius and more shielding

Question 11

What are the products when group 2 elements react with water

Answer 11

Hydroxide and hydrogen gas

Question 12

What is oxidised and what is reduced in a reaction between group 2 metal and water

Answer 12

Metal- oxidised
Hydrogen from each water - reduced

Question 13

What is formed when group 2 oxides react with water

Answer 13

Metal hydroxide

Question 14

List 2 properties of halogens

Answer 14

Low melting and boiling points
Exist as diatomic molecules

Question 15

Trend in boiling point down group 7

Answer 15

Increases because size of atom increases
More electrons(more London forces)

Question 16

Trend in reactivity down group 7

Answer 16

Decreases because
Atomic radius increases
Electron shielding increases
Ability to gain electron decreases

Question 17

Define disproportionation

Answer 17

The oxidation and reduction of the same element in a redox reaction

Question 18

Why is chlorine added to drinking water

Answer 18

Kills bacteria in the water and makes it safer to drink

Question 19

How can you test for carbonate Ions

Answer 19

Add strong acid to the sample
Collect the gas produced
Pass through lime water

Question 20

Positive test- carbonate ions

Answer 20

Fizzing

Lime water turns cloudy

Question 21

Test for sulfate ions

Answer 21

Dilute hydrochloric acid and barium chlorine to the sample

Question 21

Test for sulfate ions

Answer 21

Dilute hydrochloric acid and barium chlorine to the sample

Question 22

Positive test- sulfate ions

Answer 22

White precipitate

Question 23

Test for halide ions

Answer 23

Dissolve sample in water
Add aqueous silver nitrate
Record colour change
If difficult to distinguish colour add aqueous ammonia
Note solubility

Question 24

Positive result- halide ions

Answer 24

Cl-: white precipitate Br-: cream precipitate I-: yellow precipitate

Question 25

Order or qualitative tests

Answer 25

Carbonate,sulfate,halide

Question 26

Test for ammonium ions

Answer 26

Sodium hydroxide and warm Test gas with red litmus paper

Question 27

Positive ammonium test

Answer 27

Red litmus paper turns blue Ammonia smells

Question 28

What does a system mean in a chemical reaction

Answer 28

The atoms and bonds involved in the chemical reaction

Question 29

Explain the law of conservation

Answer 29

The amount of energy I am isolated system remains the same. Energy cannot be destroyed or created if can only be transferred

Question 30

What energy change is breaking bonds associated with

Answer 30

Energy is taken in to break bonds- endothermic

Question 31

What energy change is making bonds associated with

Answer 31

Energy is released to make bonds- exothermic

Question 32

What is an endothermic reaction

Answer 32

A reaction with an overall positive enthalpy change

Question 33

What is an exothermic reaction

Answer 33

A reaction with an overall negative enthalpy change

Question 34

What does activation energy mean

Answer 34

The minimum energy required for a reaction to take place

Question 35

What are standard conditions

Answer 35

100kPa 298K

Question 36

What does in standard state mean

Answer 36

The state an element/ compound exists at in standard conditions

Question 37

Define enthalpy change of formation

Answer 37

The energy change that takes place when 1 mole of a compound is formed from its constituent elements in their standard state under standard conditions

Question 38

Define enthalpy change of combustion

Answer 38

The energy change that takes place when 1 mole of a substance is completely combusted

Question 39

Define enthalpy change of neutralisation

Answer 39

The energy change that takes place when 1 mole of water is formed from a neutralisation reaction

Question 40

What does enthalpy change of reaction mean

Answer 40

The energy change associated with a given reaction

Question 41

How can you calculate enthalpy change from experimental data

Answer 41

Q=mc🔺️T where m is mass of substance being heated c is the specific heat capacity of that substance and 🔺️T is the change in temperature

Question 42

What are the advantages of using a bomb calorimeter

Answer 42

Minimises heart loss Pure oxygen used ensures complete combustion

Question 43

Why might experimental methods for enthalpy determination not be accurate

Answer 43

Heat is lost to surroundings Not in standard conditions Reaction may not go to completion

Question 44

What does average bond enthalpy mean

Answer 44

The mean energy required to break 1 mole of bonds in gaseous molecules

Question 45

How to calculate enthalpy change of reaction using average bonds enthalpies

Answer 45

🔺️H=sum of(bond enthalpies of reaction)- sum of (bond enthalpies of products)

Question 46

What is the equation used to calculate rate

Answer 46

Rate=change in concentration/ time

Question 47

Unit for rate of reaction

Answer 47

Mol dm^-3 s ^-1

Question 48

What must particles do in order to react

Answer 48

Collide with sufficient energy and correct orientation

Question 49

Do most collisions result in a reaction

Answer 49

No

Question 50

Factors that effect rate of reaction

Answer 50

Temperature Pressure Concentration Surface area Catalyst

Question 51

Affect of temperature on rate

Answer 51

Higher proportion of particles have energy greater than the activation energy so more successful collisions

Question 52

Increasing pressure/ concentration on rate

Answer 52

More particles in a given volume

Question 53

How to calculate rates from a concentration time graph

Answer 53

Draw a tangent Work out gradient Change in y/ change in x

Question 54

What is catalyst

Answer 54

A substance which increases the rate is reaction but is not used up in the reaction

Question 55

How do catalysts work

Answer 55

They provide an alternate reaction pathway so more particles have sufficient energy so increases the reaction rate

Question 56

Homogenous catalyst

Answer 56

A catalyst in the save phase as reactants

Question 57

heterogeneous catalyst

Answer 57

Catalyst in a different phase to reactants

Question 58

Catalytic convertors

Answer 58

Present in vehicles to reduce toxic emissions and prevent photochemical smog

Question 59

Define activation energy

Answer 59

Minimum energy needed for a reaction to occur

Question 60

Features of Boltzmann distribution

Answer 60

Area under curve=total number of molecules Curve starts at the origin Curve does not touch energy axis Only molecules with energy more than the activation energy can react

Question 61

Dynamic equilibrium

Answer 61

Rate of forward reaction equals rate of reverse reaction and concentration of reactants and products remain constant in a closed system

Question 62

What factors effect the position of equilibrium

Answer 62

Concentration of reactants/ products Pressure Temperature

Question 63

Le Chatelier's principle

Answer 63

If a system at equilibrium is disturbed the equilibrium moves in the direction that tends to reduce the disturbance

Question 64

What effect does a catalyst have on the position of equilibrium

Answer 64

No effect

Question 65

What condition effects the value of Kc

Answer 65

Temperature

Question 66

What type of system is Kc relevant for

Answer 66

Homogenous systems in equilibrium

Question 67

What does Kc mean for the position of equilibrium

Answer 67

Greater than one = over to the right Less than one= to the left

Question 68

Effect of temperature on equilibrium

Answer 68

Increase temp= shifts to endothermic reaction