Chemistry topic 4-chemical changes

Question 1

What is the range of acids on the ph scale?

Answer 1

0-6

Question 2

What is the range of alkalis in the ph scale?

Answer 2

8-14

Question 3

What is neutral on the ph scale?

Answer 3

7

Question 4

How can you measure the ph of a solution?

Answer 4

1. An indicator is date that changes colour depending on ph
2. A ph probe attached to a ph meter can be used to electronically measure the ph

Question 5

What is an acid?

Answer 5

A substance that forms aqueous solutions and has a ph of less then 7

Question 6

What is a base?

Answer 6

A substance with a ph greater then 7

Question 7

What is an alkali?

Answer 7

Base that dissolves in water and ph greater then 7

Question 8

What practical can be used to analyse the concertration of a solution?

Answer 8

Titration

Question 9

What is the method for the titration practical?

Answer 9

1. Using a pipette and pipette filler add a set volume of alkali to a conical flask
2. Add 2-3 drops of indicator
3. Use a funnel to fill a burette of an acid with a known concerntration
   4.add a small amount of acid to the alkali and swirl
4. Indicator changes colour when all alkali had been neutralised
5. Record final volume of acid in the burette and use it to calculate the volume of acid used to neutralise the alkali

Question 10

What do acids produce in water?

Answer 10

Protons

Question 11

What happens to acids in aqueous solutions?

Answer 11

They ionise and produce hydrogen ions

Question 12

what is ph a measure of?

Answer 12

the concentration of hydrogen ions

Question 13

for every decrease of 1 on the ph scale how much does the concentration of h+ ions increase?

Answer 13

by a factor of 10

Question 14

what are metal oxides and metal hydroxides ?

Answer 14

bases

Question 15

what is formed when metal oxides and metal hydroxides react with acids?

Answer 15

salt and water

Question 16

what do acids and metal carbonates produce?

Answer 16

carbon dioxide

Question 17

what does the reactivity series show?

Answer 17

how well metals react

Question 18

how is a metals reactivity determined?

Answer 18

by how easily they lose electrons

Question 19

what happens when metals react with water and acid ?

Answer 19

they lose electrons and form positive ions

Question 20

how is the speed of a metals reaction indicated?

Answer 20

by the rate of bubbles of hydrogen given off

Question 21

what is oxidation?

Answer 21

loss of electrons

Question 22

what is reduction?

Answer 22

gain of electrons

Question 23

how do metals higher then carbon in the reactivity series have to be extracted?

Answer 23

using electrolysis

Question 24

how are metals below carbon extracted?

Answer 24

by reduction using carbon

Question 25

what is a redox reaction?

Answer 25

when reduction and oxidation happen at the same time

Question 26

what happens in a displacement reaction?

Answer 26

a more reactive metal will displace a less reactive metal from its compound

Question 27

in a displacement reaction what gains electrons and is reduced?

Answer 27

the metal ion

Question 28

in a displacement reaction what loses electrons and is oxidised?

Answer 28

the metal atom

Question 29

what is shown in an ionic equation?

Answer 29

the particles and the products

Question 30

what does electrolysis mean?

Answer 30

splitting up with electricity

Question 31

what moves towards the anode in electrolysis?

Answer 31

negative ions

Question 32

what moves towards the cathode in electrolysis?

Answer 32

positive ions

Question 33

what happens during electrolysis?

Answer 33

an electric current is passed through an electrolyte and the ions move towards the electrodes and the compound decomposes

Question 34

how can metals be extracted from their ores?

Answer 34

using electrolysis

Question 35

why cant an ionic solid be electrolysed?

Answer 35

the ions are fixed and cant move

Question 36

what does a half equation show?

Answer 36

the reactions at the electrodes

Question 37

what is important to remember when combining half equations?

Answer 37

the number of electrons needs to be the same for each half equation