A2 Chemistry Unit 5

Front 1

Why is e.m.f the same when operating in alkaline or acidic conditions?

Back 1

Overall reaction is the same

Front 2

Define transition metal

Back 2

A metal that can form one or more stable ions with a partially filled d-subshell.

Front 3

Why is electron affinity exothermic?

Back 3

Net attraction between nucleus and added electron.

Front 4

Why does entropy increase in terms of movement of particles?

Back 4

Molecules VIBRATE more, so more disorder.

Front 5

Why do complex ions become more stable in reaction?

Back 5

Positive entropy change, so increase in number of particles.

Front 6

How do T-metal catalysts work?

Back 6

By changing oxidation states by gaining or losing electron in d orbital.

Front 7

Word for excessive amount eg blood fluid

Back 7

Plethora

Front 8

What agent is zinc?

Back 8

Reducing agent. It can reduce Cr3+ to Cr2+

Front 9

Name 3 physical properties for Transition metals

Back 9

- High density

- High melting and Boiling points

- All very similar ionic radii

Front 10

Name 3 chemical properties for transition metals

Back 10

- Form complex ions (bonds to ligands)

- Form coloured ions

- Good catalysts

Front 11

What is a complex ion

Back 11

A metal ion surrounded by co-ordinately bonded ligands

Front 12

Spectrometry used to find concentrations of transition metal ions. How?

Back 12

- White light shone through filter

- Filter only let's colour of light through

- Colour of light passes through sample then to colorimeter.

- Colorimeter calculates how much light absorbed by sample.

- More light absorbed = higher concentration of ions

Front 13

Cr2O7(2-) in alkali, OH-, forms

Back 13

2CrO4(2-) + H+

This is reverse reaction, exists in equilibrium

Front 14

Dichromate, Cr2O7(2-), can be reduced by good reducing agent?

What's the equation

Back 14

- Zinc and dilute acid

Cr2O7(2-) + 3Zn + 14H+ --> 3Zn(2+) + 2Cr(3+) + 7H2O

Front 15

Zinc reduces Cr(3+) to...

Back 15

Cr(2+)

2Cr(3+) + Zn --> Zn(2+) + 2Cr(2+)

Green/violet Blue

Requires inert atmosphere because Cr(2+) is very unstable it will oxidise back to Cr(3+)

Front 16

Can oxidise Cr(3+) to CrO4(2-) using H2O2 in alkaline

Back 16

2Cr(3+) + 10OH(-) + 3H2O2 --> 2CrO4(2-) + 8H2O

Front 17

Equation to oxidise Co(2+) to Co(3+)?

Co(2+) is more stable

Back 17

2Co(2+) + H2O2 --> 2Co(3+) + 2OH-

Front 18

[Co(H2O)4(OH)2] - blue precipitate can also be written as

Back 18

Co(OH)2

Front 19

Increasing surface area of heterogeneous catalyst

Back 19

Increases number of molecules that can react at the same time, so increases rate of reaction

Cos reaction happens on surface of the catalyst

Front 20

How can you make catalysts more effective

Back 20

Use support mediums. For example ceramic lattice coated in rhodium is used in catalytic converters.

Minimises cost because only thin layer of rhodium catalyst used

Front 21

The 3 examples of heterogeneous catalysts are:

Back 21

- Iron (Fe) in Haber process, N2 + 3H2 --> 2NH3

- V2O5, Contact process making sulfuric acid, SO2 + (1/2)O2 --> SO3

- Cr2O3 making methanol from CO, 2H2 + CO --> CH3OH

Front 22

Explain how homogeneous catalysts work

Back 22

Homogeneous catalysts forms intermediate species. Catalyst reacts with reactants to form intermediate which then reacts with product to reform catalyst. Activation energy for this is lower than to form products from reactants.

Front 23

Homogeneous autocatalysis definition and example

Back 23

- Product of reaction acts as a catalyst so as reaction progresses, product increases so reaction speeds up

2MnO4(-) + 16H+ + 5C2O4(2-) --> 2Mn(2+) + 8H2O + 10CO2

Front 24

Metal that's easier to oxidise, lose electrons, has a more

Back 24

Negative electrode potential

Front 25

Half cell representation - more negative half cell (oxidised) starts on

Back 25

Left, with more positive reduced on the right

Front 26

Strongest reducing and strongest oxidising agent?

Back 26

Strongest oxidising = MnO4(-) - most positive left hand substance

Strongest reducing = Mg - most negative right hand substance

Front 27

Why would industrial companies carry out reactions higher than feasible temperature

Back 27

To speed reaction up

Front 28

Describe a standard hydrogen electrode potential

Back 28

- hydrogen gas

- 1.00 mol dm-3

- 298k and 100kpa

- platinum electrode

Front 29

Oxidation (negative cathode) and reduction (positive cathode) happens on which parts of cell convention

Back 29

Oxidation (negative cathode) - LEFT

reduction (positive cathode) - RIGHT

MOST NEGATIVE E/V TO MOST POSITIVE E/V

Front 30

Metals and non metals are best for which agents

Back 30

Metals are better reducing agents because they like to lose electrons and get oxidised so more reactivate metals have more negative electrode potentials - reducing agent

Non metals are better oxidising agents because they like to gain electrons so more reactive non metals have more positive electrode potentials, oxidising agents

Front 31

Mg reacts with steam to form? And what is the product and its colour

Back 31

MgO + H2

Brilliant white flame

MgO = white solid/ash

Front 32

Na2O forms what flame and what is Na2O

Back 32

Yellow flame

White ash

Front 33

When a question contains DILUTE and AMPHOTERIC for when writing an equation you must include ... In the reactants

Back 33

Water - H2O

Front 34

[Fe(H2O)]2+ + NH3 forms

Back 34

NH4+ and Fe(H2O)4(OH)2

Front 35

Mean bond enthalpies for what type of molecules are the same?

Back 35

Diatomic

Front 36

Mg(OH)2 is a weak alkaline solution, why?

Back 36

It's not very soluble in water so few OH- ions are produced

Front 37

SiO2 is macromolecular so is insoluble but is it acidic or basic

Back 37

Acidic

Front 38

covalent oxides will neutralise...

Back 38

Alkaline because covalent oxides are acidic

Front 39

Writing equation for oxidation of complex ion requires what in reactants

Back 39

Oxygen and water

Front 40

What to remember when calculating enthalpy formation etc

Back 40

Divide answer by 2 if 2 moles formed in equation

Front 41

Bond enthalpy DATA

Back 41

arrows go down then up

Front 42

When reacting with ammonia for t-metal equations, what must be used because NH3 is basic

Back 42

OH- ions to get rid of H+ acid so OH- must be used in equation to make alkali due to NH3 being basic

Front 43

Bond enthalpy is .... Of atomisation

Back 43

Double atomisation

Front 44

Equilibrium moving to the side of the electrons makes the E/V more

Back 44

Negative - in relative to hydrogen equilibrium