Reactions

Question 1

When you have a negative total energy what reaction is this

Answer 1

Endothermic is positive
Exothermic is negative

Question 2

What is activation energy

Answer 2

The energy required to start a reaction

Question 3

Explain an exothermic reaction graph

Answer 3

Starts high then has the activation energy which will then make the energy decrease with the energy change being negative

Question 4

Why can’t solid ionic compounds be electrolysed

Answer 4

Due to ions not being able to flow
Molten ionic compounds or solutions of ionic compounds can be due to ions being able to flow

Question 5

Explain the electrolysis of MOLTEN compounds (PbBr)

Answer 5

The first part of the formula is the metal which is discharged at the cathode (so Pb will be discharged at the cathode)

The second part of the equation is the non metal which is discharged at the anode (Br) this returns back to its elemental name (bromide - bromine)

Question 6

What is discharged at the cathode and anode if the electrolyte is molten sodium chloride

Answer 6

Cathode - sodium

Anode - chlorine

Question 7

How does electrolysis of a solution (aq) work

Answer 7

At the cathode hydrogen is always discharged UNLESS COPPER, LEAD OR SILVER ions are present

At the anode oxygen is always discharged at UNLESS THERE IS A HALIDE ION (CHLORIDE, BROMIDE, IODIDE)

Question 8

What is discharged at the cathode and anode for (aq) potassium bromide

Answer 8

Cathode - hydrogen

Anode - bromine

Question 9

What are anions and cations

Answer 9

Anions are negative ions that lose electrons at the anode. This is oxidation

Cations are the positive ions that gain electrons at the cathode. This is reduction

Question 10

Explain how one positive ion forms atoms at the negative electrode

Answer 10

The cation (positive ion) will go to the cathode there it will receive electrons they will bond causing the positive ion to be reduced as it is gaining electrons at the cathode and forming an atom