Reactivity 3.1

Question 1

Ionic/Arrhenius theory

Answer 1

Acids are substances that dissociate in aqueous solution to produce H+ ions (protons)

Question 2

What happens when protons combined with water?

Answer 2

Hydronium ions are formed (H3O+)

Question 3

How can an acid be neutralised?

Answer 3

By a base to form salt or water

Question 4

Alkali

Answer 4

Soluble bases which form OH- in solution

Question 5

Bronsted Lowry theory

Answer 5

An acid is a substance that can donate a proton and a base is a substance that can accept a proton

Question 6

Amphoteric

Answer 6

Can act as an acid or base

Question 7

When Bronsted Lowry acid loses a proton,

Answer 7

It forms a conjugate base

Question 8

Conjugate acid-base pair

Answer 8

Differs by a single proton H+

Question 9

pH scale

Answer 9

Measure of the hydrogen ion concentration in aqueous solution

Question 10

pH when volume or dilution

Answer 10

pH value is independent of volume of solution. Changes when diluted.

Question 11

pH logarithmic scale

Answer 11

A change of one unit of pH represents a change by 10x in the hydrogen ion concentration

Question 12

Kw

Answer 12

Ionic product constant for water

Question 13

Monoprotic acids

Answer 13

Contain one acidic hydrogen atom (acid concentration = hydrogen concentration)

Question 14

Diprotic acids

Answer 14

Contains two acidic hydrogen atom (hydrogen concentration = 2x acid concentration)

Question 15

Two ways to determine pH value of solution

Answer 15

Universal indicator and a pH meter.

Question 16

Strong acids in aqueous solution

Answer 16

Completely dissociate into their ions

Question 17

Weak acids in aqueous solution

Answer 17

Partially dissociate into their ions, the weaker the acid/base, the less degree of dissociation

Question 18

Ka

Answer 18

Acid dissociation constant. The smaller the value of k, the weaker the acid.

Question 19

Electrical conductivity (strong vs weak acids)

Answer 19

The stronger the acid/base, the high the electrical conductivity.

Question 20

pH (strong vs weak acids)

Answer 20

The stronger the acid, the lower the pH (compared to the pH of a weak acid of the same concentration)

Question 21

Chemical reactivity (weak and storng acids)

Answer 21

Acids react with metals to produce H2 gas and undergo neutralisation with metals. Weaker acids have lower reaction rates.

Question 22

Strong acids - conjugate base

Answer 22

Weak conjugate bases as acid has fully dissociated. Little tendency to gain a proton

Question 23

Weak acids - conjugate bases

Answer 23

Easily accepts protons from water

Question 24

Acids neutralisation

Answer 24

Reacting with a base to form salt and water. Exothermic.

Question 25

Why are neutralisation reactions exothermic?

Answer 25

The only reaction that takes place is the reaction between hydrogen and hydroxide ions to form water and this is exothermic.

Question 26

Equivalence point

Answer 26

When there are equal amounts of acid and base present in the flask

Question 27

How can you predict equivalence point?

Answer 27

Where there is a sharp jump on the graph

Question 28

Methyl orange indicator

Answer 28

Red in acid to yellow in alkali

Question 29

Bromothymol blue

Answer 29

Yellow in acid to blue in alkali

Question 30

Phenolphthalin

Answer 30

Colourless in acid to pink in alkali

Question 31

[H+] =

Answer 31

10 ^ (-pH)