Ions and electrolysis

Question 1

Cl2 + 2KBr > 2KCl + Br in water separates into which ions

Answer 1

Cl2 + 2K+ + 2Br- > 2K+ + 2Cl- + Br2

Therefore:

Cl2 + Br- > 2Cl- + Br2

Question 2

Why can we simplify this:

Cl2 + 2K+ + 2Br- > 2K+ + 2Cl- + Br2

Answer 2

Because K+ is a spectator ion

So, the metal involved is irrelevant

Question 3

What is an ion?

Answer 3

An ion is a particle that is charged due to a gain or loss of electrons

Question 4

What are ionic compounds?

Answer 4

Ionic compounds are formed of positive and negative ions held together by electrostatic attraction in a lattice

Question 5

Metals form _______ ions

Non-metals form _______ ions

Answer 5

Positive

Negative

Question 6

Why does ionic formulae work

Answer 6

Because a compound is neutral so the positive and negative ions in an ionic compound must balance

Question 7

Sulfate

Answer 7

SO4{2-}

Question 8

Carbonate

Answer 8

CO3{2-}

Question 9

Nitrate

Answer 9

NO3{-}

Question 10

Hydroxide

Answer 10

OH{-}

Question 11

Ammonium

Answer 11

NH4{+}

Question 12

Sodium sulphate

Answer 12

Na {+}. SO4{2-}. -doesn’t matter

Na2SO4

Question 13

Magnesium nitrate

Answer 13

Mg{2+}. NO3{-}

Mg(No3)2

Question 14

Strontium sulfate

Answer 14

Sr{4+} SO4{2-}
Sr2(SO4)2
SrSO4

Question 15

Ionic compounds are solid st room temperature and have high melting and boiling points

Answer 15

Electrostatic attractions between positive and negative ions are very strong. This is because a lot of energy is required to break them

E.g. NaCl melts at c. 800•C

Question 16

Ionic compounds cannot conduct electricity as solids

Answer 16

Electricity requires charges that can move. Ions are fixed in the ionic lattice and cannot move so cannot conduct

Question 17

Ionic compounds can conduct electricity in molten or aqueous state

Answer 17

Ions are free to move so it can carry a charge and conduct electricity

Question 18

Electrolysis-

Answer 18

Electrolysis is the breakdown of ionic compounds into elements using electricity

Question 19

Molten resultant elements

Answer 19

The elements in the ion

Question 20

The passing of electrons creates (electrolysis)

Answer 20

A circuit

Question 21

Cryolite is added to aluminium oxide to

Answer 21

Reduce it’s melting point

Question 22

Aluminium oxide electrolysis

Answer 22

2Al2O3 > 4Al + 3O2

Question 23

Water electrolysis equation

Answer 23

H2O > H{+} + OH{-}

Question 24

PANCake

Answer 24

Positive = Anode Negativ = Cathode

Question 25

Half equations

Answer 25

include electrons

Question 26

Full equations

Answer 26

dont include electrons

Question 27

Molten electrolysis summary >

Answer 27

A negative and positive electrode are charged with electricity. The anode attracts the negative ion and the cathode attracts the positive ion the transfer of electrons from and to each electrode creates a circuit.

Question 28

2 rules of Aqueous Electrolysis

Answer 28

> Anode: if ionic compound contains a group 7 element the group 7 element is formed, if not O2 is formed > Cathode: if the metal is more reactive than H, H is made if not the metal is made

Question 29

Other product of aqueous electrolysis

Answer 29

e.g. Na+ Cl- H+ OH- > NaOH (Sodium Hydroxide) - strong alkali used for cleaning product

Question 30

Ionic compounds at room temp.

Answer 30

solid

Question 31

electrostatic attractions are strong/weak

Answer 31

strong

Question 32

Why can't ionic compounds conduct electricity?

Answer 32

Electricity requires charges that can move. Ions are fixed in ionic lattice so cannot carry charge. They can conduct in molten or aqueous states

Question 33

Test for Cl2

Answer 33

Litmus paper (pos = bleaches white from blue)

Question 34

At anode (OILRIG)

Answer 34

Oxidation

Question 35

At cathode (OILRIG)

Answer 35

Reduction

Question 36

Advantages of Ionic dot and cross diagrams

Answer 36

> Show relative size of ions and how electrons arranged

Question 37

Disadvantages of Ionic dot and cross diagrams

Answer 37

> No info about structure of lattice in 3 dimensions

Question 38

Advantages of 3D models

Answer 38

> Show relative sizes of ions | > Show regular pattern in an ionic compound

Question 39

Disadvantages of 3D models (ionic bonding)

Answer 39

> You can only see outer layer of compound

Question 40

Advantages of Ball and stick diagrams (ionic bonding)

Answer 40

> Show 3D arrangement of ions > Show the regular pattern in an ionic lattice > Show that the crystal extends beyond what is shown in the diagram

Question 41

Disadvantages of Ball and stick diagrams (ionic bonding)

Answer 41

> May not show relative size of ions | > Show gaps between ions when in reality there are no gaps