Topic 5 Redox

Question 1

What does the term “oxidation” mean in redox chemistry?

Answer 1

Oxidation refers to the loss of electrons or an increase in oxidation number.

Question 2

What does the term “reduction” mean in redox chemistry?

Answer 2

Reduction refers to the gain of electrons or a decrease in oxidation number.

Question 3

What is a reducing agent?

Answer 3

A substance that donates electrons and gets oxidized in a redox reaction.

Question 4

What is an oxidizing agent?

Answer 4

A substance that accepts electrons and gets reduced in a redox reaction.

Question 5

State the oxidation number of oxygen in most compounds.

Answer 5

The oxidation number of oxygen is typically -2, except in peroxides (-1) and when bonded to fluorine (+2).

Question 6

What is the sum of oxidation numbers in a neutral compound?

Answer 6

The sum of oxidation numbers in a neutral compound is 0.

Question 7

How do you identify a redox reaction?

Answer 7

A redox reaction involves both oxidation and reduction
processes, where oxidation numbers change.

Question 8

What is the role of half-equations in redox reactions?

Answer 8

Half-equations show the oxidation or reduction process separately, helping to balance redox reactions.

Question 9

Write the formula for calculating moles in titration.

Answer 9

Moles= conc/ vol

Question 10

Three types of chemical reactions

Answer 10

1. Precipitation
2. Acid-base
3. Oxidation-reduction

Question 11

6 rules for solubility of salts in water

Answer 11

1. Most nitrate salts are soluble
2. Most salts including alkali metal ions and the ammonium ion are soluble
3. Most chloride, bromide and iodide salts are soluble, exceptions are Ag, Hg and Pb ions
4. Most hydroxide salts are only slightly soluble, important soluble ions are NaOH and KOH.
5. Most sulfide, carbonate, chromate and phosphate salts are slightly soluble

Question 12

Solution calculations method

Answer 12

1) Identify species present in combine solution and determine what reaction occurs
2) Write balanced net ionic equation
3) Calculate moles of reactants
4) Determine limiting reagents
5)Calculate moles of products
6) Convert to grams or whatever unit is required

Question 13

Writing and balancing redox method (acidic)

Answer 13

1) Identify the atoms that are oxidised and reduced, using oxidation number method
2) Balance the half equation
- make sure same number of atoms on each side
- if oxygen is present then balance by adding water to other side
- if hydrogen is present then balance them by adding H+ ions to other side
- make sure that the charge is balanced on each side, do this by adding electrons then if needed multiply one of the half equations to make sure it’s balanced.