Acids

Question 1

Name 4 common acids

Answer 1

HCl
H2SO4
HNO3
CH3COOH

Question 2

What is an acid?

Answer 2

A species that is a proton donor

Question 3

Why is an acid a proton donor?

Answer 3

They release H+ ions (protons) when dissolved in water

Question 4

Name a strong acid

Answer 4

HCl

Question 5

What makes an acid a strong acid?

Answer 5

When it dissolves, all of the acid molecules dissociate to release H+ ions

Question 6

Name a weak acid

Answer 6

CH3COOH

Question 7

What makes an acid a weak acid?

Answer 7

When is dissolves, only a small proportion of the acid molecules dissociate to release H+ ions

Question 8

Name 3 common bases

Answer 8

NaOH
KOH
NH3

Question 9

What are general bases?

Answer 9

Metal oxides and metal carbonates

Question 10

What are bases?

Answer 10

A species that is a proton acceptor

Question 11

What do bases do?

Answer 11

Accept protons donated by the acid

Question 12

What are alkalis?

Answer 12

A type of base that dissolves in water forming OH- ions

Question 13

Name a strong base

Answer 13

NaOH

Question 14

What makes a strong base a strong base?

Answer 14

When it dissolves, all of its OH- ions are available to accept protons

Question 15

What makes a weak base a weak base?

Answer 15

Only a small proportion of the base molecules will accept protons

Question 16

Name a weak base

Answer 16

NH3

Question 17

Ionic equation for when an acid is added to water

Answer 17

HCl + aq ———-> H+ + Cl-

Question 18

Ionic equation for the formation of water in a neutralisation reaction

Answer 18

H+ + OH- ———-> H2O

Question 19

What is a salt?

Answer 19

Any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion such as an ammonium ion

Question 20

The three ways salts can be formed

Answer 20

Neutralising acids with carbonates, bases and alkalis

Question 21

What happens when an acid is added to a carbonate?

Answer 21

Salt, water and carbon dioxide is produced

Question 22

What happens when an acid is added to a base?

Answer 22

Salt and water

Question 23

What happens when an acid is added to a alkali?

Answer 23

Salt and water

Question 24

What is a titration?

Answer 24

An experiment in which an acid is added to a basic solution or the other way round until the reactants just neutralise each other

Question 25

What are the 10 steps to a titration?

Answer 25

1) The burette is set up containing the standard solution 2) Initial volume is recorded 3) The accurate known volume of the other solution is added to a flask using a volumetric pipette 4) Small amount of indicator is added to the flask 5) A white tile is placed underneath the flask to ensure the colour change shows 6) The standard solution is slowly added to the flask 7) The flask is swirled gently to ensure mixing 8) Stop adding when indicator just changes permanently 9) Final volume recorded 10) Repeat until 2 titres are concordant within 0.1 cm3 of each other

Question 26

Name 3 possible indicators for a titration

Answer 26

Methyl orange Bromothymol blue Phenolphthalein

Question 27

Outline the use of methyl orange

Answer 27

Red in acid Yellow in base Orange as the end point colour

Question 28

Outline the use of bromothymol blue

Answer 28

Yellow in acid Blue in base Green as the end point colour

Question 29

Outline the use of phenolphthalein

Answer 29

Colourless in acid Pink in base Pale pink as the end point colour

Question 30

What is important to note about the use of phenolphthalein?

Answer 30

The end point colour of pale pink is assuming that a base is being added to acid but if an acid is being added to a base, the end point is colourless

Question 31

What is a systematic error?

Answer 31

A constant error due to a piece of equipment like a balance being incorrectly calibrated

Question 32

What is a random error?

Answer 32

An error that may not always occur in an experiment like an air bubble in the burette

Question 33

What is margin of error?

Answer 33

Equipment limits of precision for equipment used to take measurements