2.1.5 Redox

Question 1

What is the oxidation number of an atom in its natural form?

Answer 1

0

Question 2

What is the oxidation number of oxygen in peroxide?

Answer 2

-1

Question 3

What is the oxidation number of hydrogen in metal hydrides?

Answer 3

-1

Question 4

What is the oxidation number of group 1 and 2?

Answer 4

+1, +2

Question 5

What is the oxidation of fluorine in compounds?

Answer 5

-1

Question 6

How do you determine the oxidation number of an element in a molecular (covalently bonded) ion?

Answer 6

The sum of the oxidation numbers of all elements in the ion equal the charge of the ion

Question 7

How do you write the formula for a compound with elements of known oxidation numbers

Answer 7

Balance oxidation numbers to make the sum of the oxidation numbers equal to zero or to the charge of the ion

Question 8

How is oxidation number indicated for elements with multiple oxidation states?

Answer 8

Roman Numerals

Question 9

What are formulas for Iron (II) chloride and Iron (III) chloride?

Answer 9

FeCl2 (Fe has oxidation number +2)
FeCl3 (Fe has oxidation number +3)

Question 10

What is oxidation and reduction in terms of electron transfer?

Answer 10

Oxidation - loss of electrons
Reduction - gain of electrons

Question 11

What is oxidation and reduction in terms of oxidation number?

Answer 11

Oxidation - increase in reduction number
Reduction - decrease in oxidation number

Question 12

What happens in reaction:
2Mg + O2 → 2MgO

Answer 12

Mg is oxidised from 0 to +2
O is reduced from 0 to -2

Question 13

What happens in reaction:
4Fe + 3O2 → 2Fe2O3

Answer 13

Fe is oxidised from 0 to +3
O is reduced from 0 to -2

Question 14

What products form when a metal reacts with an acid?

Answer 14

Salt and hydrogen gas

Question 15

What is the reaction between magnesium and hydrochloric acid?

What is being oxidised and what is being reduced?

Answer 15

Mg + 2HCl → MgCl2 + H2
Mg is oxidised 0 to +2
H is reduced from +1 to 0

Question 16

What is the reaction between zinc and hydrochloric acid?

Answer 16

Zn + 2HCl → ZnCl2 + H2
Zinc is oxidised 0 to +2
H+ is reduced +1 to 0

Question 17

What is the reaction between Iron and hydrochloric acid?

Answer 17

Fe + 2HCl → FeCl2 + H2
Iron is oxidised 0 to +2
H+ is reduced +1 to 0

Question 18

How do you interpret a redox equation

Answer 18

Assign oxidation numbers, identify which elements are oxidised and reduced, and track electron loss or gain

Question 19

How can you predict the products of a redox reaction?

Answer 19

By identifying the oxidation states of the reactants, you can predict which elements will be oxidised and reduced, and determine the products