electrolytic processes

Question 1

what is an electrolyte

Answer 1

A substance which, when molten or in solution, will conduct an electric current

Question 2

what is the movement of electrons during electrolysis

Answer 2

postivey charged cations move to the negative charged electrode,cathode and negatively charged anions move to the positive electrode

Question 3

what happens during electrylosis

Answer 3

Passing a current through substances that are molten or solution means that the solution can be broken down into elements.

Question 4

what does oxidation and reduction mean in terms of the movement of electrons

Answer 4

OIL RIG - oxidation is loss , reduction is gain of electrons

Question 5

what electrodes do oxidation and reduction occur at

Answer 5

loss of electrons happen at the anode and gain of electrons happen at the cathode

Question 6

how do you write an half eautions for a reactions

Answer 6

negative electrode: X+-> X, so ionic equation must be:
X+ + e –> X, electrons gained, so positive ions are reduced

positive electrode: X- -> X, so ionic equation must be:
X –> e- + X, electrons are lost, so negative ions are oxidised

Question 7

what is the electrolysis of copper chloride solution

Answer 7

• copper(+) ions go to cathode and soild copper is produce, this is because copper is less reactive than hydrogen
• chlorine (-) ions go to the anode and chlorine gas is produced because chlorine is a halogen

Question 8

what is the electrolysis of sodium chloride solution

Answer 8

• hydrogen (+) ions go to the cathode and hydrogen gas is produced because sodium is more reactive than hydrogen
• chlorine(-) ions go to the anode and chlorine gas is produce because its a halogen ions

Question 9

what is the electrolysis of sodium sulphate solution

Answer 9

• hydrogen(+) ions go to the cathode and hydrogen gas is produced because sodium is more reactive than hydrogen
• hydroxide (-) ions go to the anode and oxygen is produced

Question 10

what is the rule for products in electrolysis

Answer 10

at the cathode - hydrogen is produced UNLESS the + ions in the ionic compound are from a metal less reactive than hydrogen.IF the metal is less reactive than hydrogen, the metal will be produced instead

at the anode - oxygen will be produced UNLESS the ionic compound contains halide ions (Cl,Br). IF there are halide ions, the halogen will be produced instead (cl2)

Question 11

what will the products of electrolysis be when the ionic compounds are molten

Answer 11

the + ions will go to the cathode

the - ions will go to the anode

Question 12

how is the electrylis of copper sulphate carried out (using unreactive electrode )

Answer 12

1. investigation using inert electrode
   a. aim is to investigate the electrolysis of copper sulfate solution using unreactive electrodes
   b. first pour some copper sulfate solution into a beaker
   c. second, place two graphite rods into the copper sulfate solution.Attach one electrode to the negative terminal of a dc supply and the other electrode to the positive terminal
   d. completely fill two small test tubes with sopper sulfate solution and position a test tube over each electrode
   e. turn on the power supply and observe what happens at each electrode
   f. test any gas produced with a glowing splint and burning splint

*anaylsis
a. copper metal is formed at the negative electrode
b. oxygen gas is formed at the positive electrode

Question 13

how is the electrolysis of copper sulfate carried out using copper electrode

Answer 13

a. aim is to investigate the elctrylsis of copper sulfate solution using non unreactive electrodes
1. pour ose copper sulfate into a beaker
2. measure and record the mass. of a piece of copper foil. attach it to the negative terminal of a dc supply, and dip the copper foil into the copper sulfate solution
3. repeat step 2 with another piece of copper foil but this time attach it to the positive terminal
4. make sure the electrodes do not. touch each other, then turn on the power supply.adjust the power supply to achieve a constant current
5.after 20 mins, turn off dc supply
6.carefully remove one of the electrodes. gently wash it with distilled water then dip it into propane/lift the electrode out and allow all the liquid to evaporate.Do not wipe the electrodes clean/measuree and record the mass of the electrode
7. repeat step 6 with the other electrode make sure you know which is which
8. repeat the experiment with fresh electrodes and different currents

Question 14

name the hazardous substance, its harm and precautopn

Answer 14

copper sulftae solution, causes skin and serious eye irritation, wear gloves and eye protection

Question 15

name another hazardous substance ,is harm and precaution

Answer 15

propane, highly flammable liquid, keep away from naked flames

Question 16

why are displacement reactions, redox reactions

Answer 16

• more reactive metal from a cation ((+) as they displace the less reactive metal, losing electrons and therefore being OXIDISED(OIL), it forms an ions as it replaces the less reactive metal in the salt solution
• less reactive metals from atoms from negative ions as they are displaced, gaining electrons and therefore being REDUCED(RIG) it forms an atom as it is replaced in salt solution

Question 17

what is the relative reactivity of metals in water

Answer 17

very reactive

Question 18

What is the relative reactivity of metals in acids

Answer 18

reactive

Question 19

what is the relative reactivity of metals in oxygen

Answer 19

not very reactive

Question 20

how can you see when a reaction takes places

Answer 20

there will be bubbles produced

Question 21

how is one metal more reactive than the other using the displacement reactions

Answer 21

• more reactive metal gradually disappears as it forms a solution
• less reactive metals coats the surface the more reactive metal