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OCR Chemistry A Level 2015 > Acids > Flashcards

Flashcards in Acids Deck (33)
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1

Name 4 common acids

HCl
H2SO4
HNO3
CH3COOH

2

What is an acid?

A species that is a proton donor

3

Why is an acid a proton donor?

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

4

Name a strong acid

HCl

5

What makes an acid a strong acid?

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

6

Name a weak acid

CH3COOH

7

What makes an acid a weak acid?

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

8

Name 3 common bases

NaOH
KOH
NH3

9

What are general bases?

Metal oxides and metal carbonates

10

What are bases?

A species that is a proton acceptor

11

What do bases do?

Accept protons donated by the acid

12

What are alkalis?

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

13

Name a strong base

NaOH

14

What makes a strong base a strong base?

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

15

What makes a weak base a weak base?

Only a small proportion of the base molecules will accept protons

16

Name a weak base

NH3

17

Ionic equation for when an acid is added to water

HCl + aq ----------> H+ + Cl-

18

Ionic equation for the formation of water in a neutralisation reaction

H+ + OH- ----------> H2O

19

What is a salt?

Any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion such as an ammonium ion

20

The three ways salts can be formed

Neutralising acids with carbonates, bases and alkalis

21

What happens when an acid is added to a carbonate?

Salt, water and carbon dioxide is produced

22

What happens when an acid is added to a base?

Salt and water

23

What happens when an acid is added to a alkali?

Salt and water

24

What is a titration?

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

25

What are the 10 steps to a titration?

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

26

Name 3 possible indicators for a titration

Methyl orange
Bromothymol blue
Phenolphthalein

27

Outline the use of methyl orange

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

28

Outline the use of bromothymol blue

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

29

Outline the use of phenolphthalein

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

30

What is important to note about the use of phenolphthalein?

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