MODULE 2: Acids and Redox

Question 1

What is an acid?

Answer 1

A compound with aqueous hydrogen ions (not just any compound with hydrogen!)

Question 2

What are strong acids?

Answer 2

Acids that completely dissociate their hydrogen ions

Question 3

What are weak acids?

Answer 3

Acids that partially dissociate their hydrogen ions

Question 4

What are bases?

Answer 4

A substance that neutralises an acid to form a salt

Question 5

What is an alkali?

Answer 5

A base that when dissolved in water releases hydroxide ions (OH-)

Question 6

What is neutralisation?

Answer 6

When the dissociated hydrogen ions from an acid react with the metal/ammonium ions of a base to form a salt and water

Question 7

What is formed when acids are neutralised by carbonates?

Answer 7

Salt, water and carbon dioxide gas

Question 8

What is titration?

Answer 8

A technique used to accurately measure the volume of one solution that reacts exactly with another solution, often used for neutralisation

Question 9

What are the uses for titrations?

Answer 9

Finding the concentration of a solution, identification of unknown chemicals, finding the purity of a substance

Question 10

What is the equipment needed for a titration?

Answer 10

Pipette, biurette and conical flask

Question 11

What is an oxidation number?

Answer 11

The number of electrons involved in bonding to another element/compound

Question 12

What is oxidation?

Answer 12

Loss of electrons/adding of oxygen

Question 13

What is reduction?

Answer 13

Gain of electrons/removal of oxygen

Question 14

When is the oxidation state zero?

Answer 14

When elements are in their natural state, when the sum of atoms in a compound adds to zero

Question 15

What is the oxidation state of ions?

Answer 15

The charge is their oxidation number (H+ = +1)

Question 16

What is the first rule of oxidation?

Answer 16

Oxidation number of elements from group 1, 2 or 3 is always +1, +2 or +3 respectively

Question 17

What is the second rule of oxidation?

Answer 17

Oxidation number of fluorine is always -1

Question 18

What is the third rule of oxidation?

Answer 18

Oxidation number of hydrogen is usually +1

Question 19

What is the fourth rule of oxidation?

Answer 19

Oxidation number of oxygen is usually -2

Question 20

What is the fifth rule of oxidation?

Answer 20

Oxidation number of chlorine is usually -1

Question 21

How do roman numerals effect oxidation numbers?

Answer 21

The roman numeral shows the oxidation state without the sign (+/-)

Question 22

What happens when the oxidation number increases?

Answer 22

Loss of electrons, more positive

Question 23

What happens when the oxidation number decreases?

Answer 23

Gain of electrons, more negative

Question 24

What are redox reactions?

Answer 24

A reaction where oxidation and reduction both occur