Chemcial Changes

Question 1

What does pH mean?*

Answer 1

Amount of hydrogen ions present in solution.
More hydrogen ion present lower pH value, more acidic
Less hydrogen ion present higher pH value, more alkali

Question 2

What is the pH of pure water

Answer 2

pH 7

Question 3

What are methods of measuring pH levels

Answer 3

Litmus paper
Universal indicator
pH probe

Question 4

What type of reaction is it when an acid + base react?

Answer 4

Neutralisation reaction

Question 5

Word and symbol equation of acids reacting with bases?

Answer 5

acid + alkali = water + salt

H + (OH) = H20`

Question 6

What is a strong acid?

Answer 6

Full ionise when dissolved in water

Question 7

What is a weak acid?

Answer 7

Partially ionise when dissolved in water?

Question 8

What is an example of a strong acid?

Answer 8

HCL

Question 9

What is an example of a weak acid

Answer 9

Carboxylic acid eg ethanolic

Question 10

What is the word equation for the disassociation of HCL

Answer 10

HCL =H+CL

Question 11

Symbol equation of the disassociation of ethanolic acid?

Answer 11

CH3COOH = H+CH3COO

Question 12

Compare the rate of reaction for strong and weak acids?

Answer 12

The rate of reaction is greater for strong acids due to increased concentration of H ions

Question 13

What happens to H+ when the pH from 5 lowers to 4?

Answer 13

H+ in solution multiply by 10

Question 14

What is the differences between strong acids and concentrated acids?

Answer 14

The concentrated acids are how many particles there are in a given volume, strength determines ionising ability

Question 15

What is the word equation for acid and an metal oxides?

Answer 15

acid + metal oxide = salt + water

Question 16

Why does this occur?

Answer 16

Metal oxides = bases

Question 17

What is the word equation for acid and metal hydroxide?

Answer 17

acid + hydroxide = salt + water

Question 18

What happens when hcl + cuo

Answer 18

HCL + CuO = Copper chloride + water

Question 19

What is the equation of sulphuric acid + potassium hydroxide?

Answer 19

H2SO4 + K(OH) = potassium sulphuric + water

Question 20

What happens when acids react with metal carbonates?

Answer 20

acid + carbonate = salt + water + carbon dioxide

Question 21

What is the reaction between sodium carbonate and hydrochloric acid

Answer 21

hydrochloric + sodium chloride = sodium chloride + water + carbon dioxide

Question 22

What is the reactivity series?

Answer 22

Potassium 
Sodium
Lithium
Calcium 
Magnesium
Carbon 
Zinc
Iron
Hydrogen
Copper

Question 23

What happens when a metal reacts with an acid?

Answer 23

acid + metal = salt + hydrogen

Question 24

How can you determine rate?

Answer 24

Rate is determined by how many bubbles produced per minute.

Question 25

What happens when a metal reacts with water?

Answer 25

metal + water = metal hydroxide + hydrogen

Question 26

What is oxidation?

Answer 26

Gain of oxygen
Loss of electrons
Loss of hydrogen

Question 27

What is reduction?

Answer 27

Loss of Oxygen
Gain of electrons
Gain of hydrogen

Question 28

Oxidation example?

Answer 28

2MG+02=2MgO

Question 29

Reduction example?

Answer 29

2CuO+C = 2Cu + CO2

Question 30

What is generated when iron oxide becomes reduced with carbon?

Answer 30

2Fe2SO3 + 3C = 4Fe + 3CO3

Question 31

What is a redox reaction?

Answer 31

The loss of electrons and gain of electrons at the same time

Question 32

Displacement reactions, word, symbol and ionic equation between iron and copper sulphate.

Answer 32

Iron + copper sulphate = iron sulphate + copper
Fe + CuSO4 = FeSO4 + Cu

Fe =Fe2 =+2e- Cu2+ +2e- = Cu

Question 33

What is electrolysis?

Answer 33

Electrolysis is the breaking down with the use of electricity.
Positive ions will move towards the cathode and gain electrons
Negative ions will move towards the anode and lose electrons