Acids, Alkalis & salts (46-47, 50) (paper 1)

Question 1

define acid

Answer 1

produces H+ in water ~ proton donors

Question 2

what pH scale do acids have

Answer 2

less than 7

Question 3

define a base

Answer 3

substance which can neutrilise an acid ~ proton acceptors

Question 4

define an alkali

Answer 4

soluble producing OH- ions in waterr

Question 5

what pH scale do alkalis have

Answer 5

greater than 7

Question 6

what colour are strong acids in universal indicator

Answer 6

red

Question 7

what colour are weak acids in universal indicator

Answer 7

orange / yellow

Question 8

what colour is water in universal indicator

Answer 8

green

Question 9

what colour are strong alkalis in universal indicator

Answer 9

purple

Question 10

what colour are weak alkalis in universal indicator

Answer 10

blue

Question 11

what is a digital way of understanding the pH of a substance

Answer 11

a pH meter

Question 12

name the three most common acids and their molecular formula

Answer 12

• Hydrochloric acid (HCl)
• Sulfuric acid (H2SO4)
• Nitric acid (HNO3)

Question 13

what type of salt would be formed from hydrochloric acid

Answer 13

metal chloride

Question 14

what type of salt would be formed from sulfuric acid

Answer 14

metal sulfate

Question 15

what type of salt would be formed from nitric acid

Answer 15

metal nitrate

Question 16

what is produced when a metal reacts with an acid

Answer 16

• salt
• hydrogen

Question 17

what is produced when a metal oxide reacts with an acid

Answer 17

• salt
• water

Question 18

what is produced when a metal hydroxide reacts with an acid

Answer 18

• salt
• water

Question 19

what is produced when a metal carbonate reacts with an acid

Answer 19

• salt
• caron dioxide
• water

Question 20

what is the difference between an alkali and a base

Answer 20

bases are insoluble, alkalis can be dissolved in water

Question 21

what is an indicator

Answer 21

something which changes colour depending on the pH of a solution

Question 22

name the indicators

Answer 22

• universal indicator
• litmus paper
• phenolphthalein
• methyl orange

Question 23

what is the colour change for litmus paper

Answer 23

• acid = red
• alkali = blue

Question 24

what is the colour change for phenolphthalein

Answer 24

• acid = colourless
• alkali = pink

Question 25

what is the colour change for methyl orange

Answer 25

• acid = red
• alkali = yellow

Question 26

what is the reaction between an acid and alkali called

Answer 26

a neutralisation

Question 27

show the chemical equation for a neutralisation reaction in the terms of H+ and OH-

Answer 27

H+ (aq) + OH- (aq) -> H2O (l)

Question 28

what is produced when ammonia reacts with an acid

Answer 28

ammonium salt

Question 29

what practicle should you do when making a soluble salt from an acid and insoluble base

Answer 29

the excess solid method

Question 30

describe the excess solid method

Answer 30

• heat the sulfuric acid
• add black copper oxide powder to excess and stir
• filter out excess copper oxide
• heat copper sulphate (blue) solution until crystalisation point and leave to cool
• filter out crystals and wash with distilled water
• leave to dry between filter paper

Question 31

why do we add copper ooxide powder to excess in the excess solid method

Answer 31

to ensure all the sulfuric acid has reacted