Module 2 - chapter 4

Question 1

What is the definition of an acid?

Answer 1

A proton donor

Question 2

Why does the state of an acid change whether it is an acid or not?

Answer 2

The hydrogen ions (protons) must be free to move in solution, so the acid has to dissolve in water

Question 3

What is the formula of phosphoric acid?

Answer 3

H3PO4

Question 4

What is the formula of ethanoic acid?

Answer 4

CH3COOH

Question 5

What is a strong acid?

Answer 5

An acid which releases all of its hydrogen ions into solution and completely dissociates in aqueous solution

Question 6

What is a weak acid?

Answer 6

An acid which only releases a small proportion of its available hydrogen ions into solution, partially dissociates in aqueous solution,

Question 7

What is an important feature of an equation showing a weak acid?

Answer 7

The equilibrium sign to show that the forward reaction is incomplete because the ionisation is a reversible reaction

Question 8

Are organic acids mostly strong or weak?

Answer 8

Weak, e.g. ethanoic acid is weak

Question 9

What class as bases?

Answer 9

Metal oxides, metal hydroxides, metal carbonates and ammonia

Question 10

What is pH a measure of?

Answer 10

Hydrogen ion concentration:

High H+ concentration = low pH

Low H+ concentration = high pH

Question 11

Do strong or weak acids react faster? Why?

Answer 11

Strong acids react faster because all H+ ions available to react at once so gives a faster reaction

Question 12

What happens to the equilibrium of the reaction when weak acids react?

Answer 12

The equilibrium shifts to the right because the H+ are being used up, this gives a slower reaction

Question 13

What is he definition of a base?

Answer 13

A proton acceptor

Question 14

What is an alkali?

Answer 14

A soluble base that releases OH- in an aqueous solution

Question 15

What is a salt?

Answer 15

A salt is formed when an acid has one or more of its hydrogen ions replaced by either a metal ion or an ammonium ion.

Question 16

What happens in neutralisation?

Answer 16

In neutralisation of an acid, H+ ions react with a bee to form a salt and water. The H+ ions are replaced by metal or ammonium ions from the base.

Question 17

What is oxidation number?

Answer 17

The number of electrons involved in bonding to a different element

Question 18

What do ionic equations include?

Answer 18

Everything but with the spectator ions removed

Question 19

What do half equations include?

Answer 19

Only the ions and the electrons added/removed

Question 20

If oxidation number increases, what has happened to the number of electrons?

Answer 20

The number of electrons has decreased as electrons are lost, the element becomes more positive

Question 21

If oxidation number decreases, what has happened to the number of electrons?

Answer 21

The number of electrons has increased as electrons are gained, the element becomes more negative

Question 22

What is the reducing agent?

Answer 22

The chemical which has been oxidised

Question 23

What is the oxidising agent?

Answer 23

The chemical which has been reduced

Question 24

What makes a good reducing agent?

Answer 24

An element which can readily lose electrons

Question 25

What makes a good oxidising agent?

Answer 25

An element which can readily gain electrons

Question 26

What is a disproportionation reaction?

Answer 26

When oxidation and reduction occur simultaneously

Question 27

What is a redox reaction?

Answer 27

When oxidation and reduction both occur