C3.3 - spec

Question 1

loss of electrons is…

Answer 1

oxidation

Question 2

gain of electrons is…

Answer 2

reduction

Question 3

look at the reaction below:
aluminium + iron(III)oxide -> aluminium oxide + iron

identify which is the:

• oxidising agent
• reducing agent

Answer 3

• iron(III) oxide is the oxidising agent as it oxidises aluminium to aluminium oxide
• aluminium is the reducing agent as it reduces iron(III) oxide to iron

Question 4

gain of oxygen is…

Answer 4

oxidation

Question 5

loss of oxygen is…

Answer 5

reduction

Question 6

look at the reaction below:
aluminium + iron(III)oxide -> aluminium oxide + iron

draw a half equation for

(a) the reactant being oxidised
(b) the reactant being reduced

Answer 6

(a) Al -> Al3+ + 3e- OXIDISED

(b) Fe3+ + 3e- -> Fe REDUCED

Question 7

what kind of ions are formed when acids are dissolved in water?

Answer 7

hydrogen ions

Question 8

what kind of ions are formed when alkalis dissolve in water?

Answer 8

hydroxide ions

Question 9

describe neutralisation (in terms of its word equation)

Answer 9

acid + alkali/base -> salt + water

Question 10

what is an aqueous neutralisation reaction?

in terms of ions

Answer 10

when hydrogen ions react with hydroxide ions to form water

Question 11

how can you predict the salt made in a neutralisation reaction?

Answer 11

first part = name of metal in alkali

second part = acid used

Question 12

write out the word equation for the following reaction:

copper(II) oxide + sulfuric acid

Answer 12

-> copper sulfate + water

NEUTRALISATION REACTION
so acid + base -> salt + water

Question 13

what is a carbonate?

Answer 13

an ionic compound which contains a carbonate ion

Question 14

write the word equation for when an acid and a carbonate react together

Answer 14

acid + carbonate -> salt + water + carbon dioxide

• carbon dioxide is produced as there is a CARBONATE present (self explanatory)

Question 15

what is a fancy word for saying bubbling/fizzing?

Answer 15

effervescence

Question 16

write the word equation for when an acid and a metal react together

Answer 16

acid + metal -> salt + hydrogen

Question 17

explain what is meant by the term ‘dilute acid’

Answer 17

an acid which has a low ratio of acid to volume in a solution

ie. MORE WATER

Question 18

explain what is meant by the term ‘concentrated acid’

Answer 18

an acid which contains a high ratio of acid to volume in a solution

ie. LESS WATER

Question 19

explain the term ‘weak acid’

in terms of ionisation of ions

Answer 19

H+ ions are partially ionised (only a small fraction of their molecules release H+ ions)

Question 20

explain the term ‘strong acid’

in terms of ionisation of ions

Answer 20

H+ ions are fully ionised (all molecules release H+ ions)

Question 21

what happens (in terms of bonds), when an acid releases hydrogen ions (H+)?

Answer 21

• a covalent bond in the acid molecule breaks

- which produces a hydrogen ion + a negatively charged ion

Question 22

how are relative acidity and alkalinity measured?

Answer 22

by pH

Question 23

in terms of pH, how do you tell how strong an acid is?

Answer 23

the closer the pH value is to 0

Question 24

in terms of pH, how do you tell how strong an alkali is?

Answer 24

the closer the pH value is to 14

Question 25

what (in terms of ions) gives an acid a pH value closer to 0?

Answer 25

larger concentration of H+ ions

Question 26

how does the pH value of a solution change if the hydrogen ion concentration increases by a factor of 10?

Answer 26

pH value decreases by 1

Question 27

so what is the relation between hydrogen ion concentration and pH value of a solution?

Answer 27

hydrogen ion conc increases (factor of 10)

pH value decreases by 1

Question 28

how do you measure the pH using a pH meter?

Answer 28

• wash pH probe with water
• put it in calibration buffer
• adjust reading to match pH of buffer solution
• wash the probe and place into solution to measure
• reecord reading on meter

Question 29

advantages of a pH probe

Answer 29

exact pH value,

Question 30

how does a universal indicator measure the pH of a solution?

Answer 30

changes colour, and then you compare it to the pH scale