acids, alkalis and titrations

Question 1

litmus is from

Answer 1

lichens

Question 2

synthetic indicators used in acid-alkali titrations

Answer 2

phenolphthalein and methyl orange

Question 3

litmus colour in acid and alkali

Answer 3

acid-red

alkali- blue

Question 4

phenolphthalein colour in acid and alkali

Answer 4

acid- colourless

alkali- pink

Question 5

methyl orange colour in acid and alkali

Answer 5

acid-red

alkali- yellow

Question 6

synthetic indicators are used to

Answer 6

show the endpoint in titrations as they have a very sharp colour change when an acid has been neutralised by an alkali and vice versa

Question 7

litmus isn’t suitable for titrations because

Answer 7

as the colour change is not sharp and it goes through a purple transition colour in neutral solutions making it difficult to determine an endpoint

Question 8

litmus is very helpful as a

Answer 8

indicator paper because it comes in red or blue versions, for dipping into solutions or testing gases

Question 9

the ph scale goes from

Answer 9

0-14 (very acidic substances have values below 0)

Question 10

all acids have a pH of

Answer 10

below 7

Question 11

all alkalis have a pH of

Answer 11

above 7

Question 12

the lower the pH is

Answer 12

the more acidic the solution is

Question 13

the higher the pH is

Answer 13

the more alkaline the solution is

Question 14

a solution of 7 is

Answer 14

neutral

Question 15

universal indicator is a

Answer 15

wide range indicator and can give only an approximate value for pH

Question 16

universal indicator is made of

Answer 16

a mixture different plant indicators which operate across a broad pH range and is useful for estimating pH of an unknown solution

Question 17

how does a universal indicator work

Answer 17

a few drops are added to the solution and the colour is matched with a colour chart which indicates the pH which matches with specific colours

Question 18

when acids are added to water

Answer 18

they form positively charged hydrogen ions (H^+)

Question 19

the presence of H^+ ions is

Answer 19

what makes a solution acidic

Question 20

when alkalis are added to water

Answer 20

they form negative hydroxide ions OH^-

Question 21

the presence of the OH^- ions is

Answer 21

what makes the aqueous solution an alkali

Question 22

the pH scale is a

Answer 22

numerical scale which is used to show how acidic for alkaline a solution is, so to measure the amount of ions present in a solution

Question 23

a neutralisation reaction occurs when

Answer 23

an acid reacts with an alkali

Question 24

when substances react together in a neutralisation reaction

Answer 24

the H^+ ions react with the OH^- ions to produce water

Question 25

the net ionic equation of all acid-base neutralisations is

Answer 25

H^+ + OH^- -> H2O