Chemistry Paper 1 #1

Question 1

What is electrolysis?

Answer 1

Electrolysis is a process that uses electric current to decompose ionic compounds into their elements.

Question 2

Define anode and cathode in electrolysis.

Answer 2

Anode is the positive electrode where oxidation occurs, and cathode is the negative electrode where reduction occurs.

Question 3

What products are formed at the anode and cathode during electrolysis of aqueous solutions?

Answer 3

At the anode, oxygen or halogens form (if halide ions are present). At the cathode, hydrogen forms if the metal is more reactive than hydrogen.

Question 4

What is the reactivity series and its importance?

Answer 4

The reactivity series is a list of metals ordered by reactivity. It helps predict how metals will react with water, acids, and other elements.

Question 5

What are redox reactions?

Answer 5

Redox reactions involve oxidation (loss of electrons) and reduction (gain of electrons) occurring simultaneously.

Question 6

Define oxidation and reduction in terms of oxygen.

Answer 6

Oxidation is the gain of oxygen, and reduction is the loss of oxygen.

Question 7

What happens when metals react with acids?

Answer 7

Metals above hydrogen in the reactivity series react with acids to produce a salt and hydrogen gas.

Question 8

Describe the general equation for a neutralisation reaction.

Answer 8

Acid + Base -> Salt + Water

Question 9

What is the pH scale?

Answer 9

The pH scale measures how acidic or basic a solution is, ranging from 0-14, with 7 being neutral.

Question 10

What distinguishes strong acids from weak acids?

Answer 10

Strong acids completely dissociate in water, while weak acids only partially dissociate.

Question 11

What is an exothermic reaction?

Answer 11

An exothermic reaction releases energy to the surroundings, usually indicated by a rise in temperature.

Question 12

What is an endothermic reaction?

Answer 12

An endothermic reaction absorbs energy from the surroundings, usually indicated by a fall in temperature.

Question 13

What are bond energy calculations used for?

Answer 13

Bond energy calculations are used to determine if a reaction is exothermic or endothermic by comparing the energy required to break bonds vs. the energy released when bonds form.

Question 14

How do you calculate energy changes using bond energies?

Answer 14

Energy change = Sum of bond energies of bonds broken - Sum of bond energies of bonds formed.

Question 15

What is a displacement reaction?

Answer 15

A displacement reaction occurs when a more reactive metal displaces a less reactive metal from a compound.

Question 16

What is the Daniell cell?

Answer 16

A type of electrochemical cell where zinc and copper electrodes create a voltage through a redox reaction in an electrolyte solution.

Question 17

Describe the function of a hydrogen fuel cell.

Answer 17

In a hydrogen fuel cell, hydrogen and oxygen react to produce water, releasing electrical energy.

Question 18

List one advantage and one disadvantage of hydrogen fuel cells.

Answer 18

Advantage: Less pollution. Disadvantage: Hydrogen storage is challenging and potentially dangerous.

Question 19

What is activation energy?

Answer 19

Activation energy is the minimum energy required for a reaction to occur by breaking initial bonds.

Question 20

What is a spectator ion?

Answer 20

A spectator ion is an ion that does not participate in the actual chemical reaction and remains unchanged.

Question 21

Explain how the reactivity series is used in predicting reactions.

Answer 21

Metals higher in the series can displace metals lower in the series from compounds, and more reactive metals will react more vigorously.