Chemistry chapter 6 (Electrochemistry)

Question 1

Define conductors?

Answer 1

Materials capable of carrying electric current, materials which have “Mobile charge carriers”

Question 2

Define Insulators?

Answer 2

Materials with no or very few free charge carriers

Question 3

Define electrolysis?

Answer 3

The process by which an electric current flows through a liquid compound or solution to cause a chemical reaction.

Question 4

Is there a chemical reaction when Electric current passes through a metal or graphite?

Answer 4

No

Question 5

Define Electrolyte?

Answer 5

substances that dissolved in water produces a solution that conducts electricity

Question 6

What do electrolytes contain?

Answer 6

ions

Question 7

Define Nonelectrolyte?

Answer 7

A substance that dissolved in water produces a solution that does not conduct electricity

Question 8

Examples of electrolytes?

Answer 8

. Molten salts
. Solutions of salt in water
. Solutions of acid
. Solutions of alkalis

Question 9

Examples of Non-electrolytes?

Answer 9

. Distilled water
. Ethanol
. Petrol
. Paraffin
. Sugar solution

Question 10

Difference between conduction of electricity in solid/liquid metals and solution?

Answer 10

In metals and liquid metals, the electricity is conducted through electrons, while in solutions the electricity is conducted through movement of ions.

Question 11

How does electrolysis work?

Answer 11

Electric current flows through the positive electrode (Anode), negative ions of the solution (anion) travel to anode and loose electrons, and are transformed into neutral molecules. The positive ions of the solution (Cation) are attracted to the negative electrode (Cathode), gain electrons and are transformed into neutral molecules.

Question 12

Properties of electrolytic conductivity?

Answer 12

. Ions flow
. Takes place is liquids and solutions (Not solids)
. Chomical decomposition takes place

Question 13

Characteristics of metallic conductivity?

Answer 13

. Electrons flow
. Takes place in solids and liquids (liquid metals)
. No chemical change takes place

Question 14

Define electrolytic cell?

Answer 14

The apparatus in which the electrolysis is carried out

Question 15

Define Electrode?

Answer 15

Rods that carry the current into and out of the solution/liquid

Question 16

Define Cathode?

Answer 16

negatively charged Electrode

Question 17

Define cation?

Answer 17

Positively charged ions

Question 18

Define Anode?

Answer 18

Positevly charged electrode

Question 19

Define Anion?

Answer 19

Negatively charged ions

Question 20

Examples of uses for sodium?

Answer 20

Sodium can be used in street lamps and as a coolant in some nuclear reactors.

Question 21

Define selective discahrge?

Answer 21

When the ions move to the anode and cathode, only one negative and one positive ion will be selected to be discharged

Question 22

How is selective discharge decided?

Answer 22

It is according to the reactivity series (for cations) and the Electrochemical series (for anions) as less reactive ions are easier to oxidize

Question 23

Factors affecting selective discharge?

Answer 23

. Position in reactivity series
. The concentration
. The type of electrode used

Question 24

Define a half equation?

Answer 24

the reaction at each electrode

Question 25

Describe how concentration may affect selective discharge?

Answer 25

If the concentration of a particular ion is high, it may be selected to be discharged even though it is higher in the electrochemical series.

Question 26

What happens if the negative ion is complex (NO3, SO4) compared to simple (Cl, Br)

Answer 26

If the negative ion is simple then that element will be produced, if it is complex however oxygen from the OH will be produced instead

Question 27

What are the 2 types of electrodes?

Answer 27

Inert Electrode and Active electrode

Question 28

Define Inert electrode?

Answer 28

Inert electrodes do not react with electrolyte and does not take part in the reaction. (Graphite, Platinum)

Question 29

Define Active electrode?

Answer 29

Active electrode will react with the electrolyte and take part in the reaction. (Copper, Gold, Mercury)

Question 30

Define dilute?

Answer 30

A concentration that has more solvent than solute

Question 31

Define concentrated?

Answer 31

Solution that contains more solute than solvent

Question 32

Define Molten?

Answer 32

melted into liquid (No presence of water)

Question 33

Electrolytic cell compared to Electrochemical cell?

Answer 33

Electrolytic cell: Electrical energy to chemical energy Electrochemical cell: Chemical energy to Electrical energy

Question 34

What is the efficancy of hydrogen fuel compared to petrol?

Answer 34

Hydrogen has a 60% efficiency compared to 35% for petrol

Question 35

How is hydrogen for fuel obtained?

Answer 35

Through electrolysis of water

Question 36

Disadvantages of hydrogen fuel?

Answer 36

. A large fuel tank required . Very few stations to top off . Engine redesign needed . Currently expensive . Non-renewable if generated using nuclear energy or fossil fuels

Question 37

Advantages of hydrogen for fuel?

Answer 37

. Renewable if produced using solar energy . Lower flammability . Virtually emission free . Non-toxic . Does not produce C02

Question 38

Explain a test for chlorine?

Answer 38

By placing blue litmus paper in the gas container, the Litmus paper turns red and then colorless.