1. 2.6 Acids, bases and salts

2. BTEOTSSSBAT:
Know that acidic and alkaline solutions are
measured on the pH scale
Identify an acid or alkali given the pH number
Know the ions that make a solution acidic or alkali
Know the products of an acid and a base reaction

3. Key words
Acid
Alkali
Neutral
pH scale
Base
Salt

8. The pH scale
pH is a measure of how acidic or alkali a solution is.
PH 7 = neutral
Indicator solution changes colour according to the
pH

9. Acids Alkalis
Neutral
The pH scale
pH < 7 pH > 7
pH = 7

10. Vinegar
Can you place the above in order in the pH scale?
The pH scale
Stomach
acid
Distilled
water Soap
powder
BleachLemon juice

11. Vinegar
The pH scale
Stomach
acid
Distilled
water
Soap
powder
Bleach
Lemon juice

12. Acids and Alkalis
What is it that determines if a solution is acid or alkali?
It’s the type of ion
H+(aq) ions make solutions acidic
and
OH–(aq) ions make them alkaline.
NB (aq) is a state symbol and it means that the
substances are in solution (aqueous)

13. Neutralisation
When does red + blue = green?
H+ (aq) +OH- (aq) H2O
When it’s a neutralisation
An acid and a base react to form a salt and water
Acid + Base Salt + Water

15. Acid or alkali?
Lemon juice
pH = 4
pH = 8
H+ (aq)
OH- (aq)Bleach Indicator turns blue
Indicator turns yellow
Acid Alkali
Sour taste Soapy feel

16. Acid or alkali?
Acid Alkali
pH = 4 pH = 8
H+ (aq) OH- (aq)
BleachLemon juice
Indicator turns blueIndicator turns yellow
Sour taste Soapy feel

17. Quick test
pH scale
1. What is the name of the scale that
measures acidity or alkalinity?

18. Quick test
pH = 7
2. If a solution is neutral what is its pH?

19. Quick test
3. Which ion makes a solution acidic?
H+ (aq)

20. Quick test
4. Which ion makes a solution alkali?
OH- (aq)

21. Quick test
Acid + Base  Salt + Water
5.What is formed when an acid and a
base react?

22. Quick test
Bases that are solutions are alkalis
All alkalis are bases but not all bases
are alkalis
6. What is the difference between
an alkali and a base?

23. 2.6 Acids, bases and salts

24. BTEOTSSSBAT:
Know how to make soluble salts
Know that metal oxide and metal hydroxides are
bases
Know how to make salts from metal oxides and
hydroxides
Know which salts are formed when metals and
acids react

25. Making soluble salts using neutralisation

26. Making soluble salts:
Reacting an acid with a metal or with an insoluble base
to give a soluble salt

27. Preparing an Insoluble Salt

29. S t r e t c h q u e s t i o n
Lead iodide is formed via precipitation by mixing aqueous
lead(II) nitrate (Pb(NO3)2) and aqueous potassium iodide
(KI)
What is meant by precipitation?
A precipitate is a solid that forms
What does the (II) in lead (II) nitrate mean?
The II show that the lead has a ionic charge of 2+

30. Balance the equation for this reaction.
Pb(NO3)2 + KI → PbI2 + KNO3
Add the state symbols (s) (l) (g) or (aq) for each
compound.
22
Pb(NO3)2 + 2KI → PbI2 + KNO3(aq)(aq) (aq)(s)

31. Find the Mr for each of the substances.
The Ar of Pb = 207
The Ar of K = 39
The Ar of I = 127
The Ar of N = 14
The Ar of O= 16
Pb(NO3)2 + 2KI → PbI2 + KNO3
207 + (14+3 x 16) x 2
331
39 + 127
166
207 + 2 x 127
461
39 + 14+ 16 x 3
101

32. What percentage of Iodine is there in lead iodine?
Pb(NO3)2 + 2KI → PbI2 + KNO3
How much would 1 mol of lead nitrate weigh?
331 166 461 101
Out of the 461 iodine is 2 x 127 so
127 x 2 x 100 = 55.1%
461
Mr = 331 so 331 g

33. 25 g of lead nitrate is reacted to produce the lead
iodine. How much lead iodine will be produced?
Pb(NO3)2 + 2KI → PbI2 + KNO3
331 166 461 101
331g would produce 461g
1g would produce 461/ 331
25g would produce (461/ 331) x 25 g
= 34.8g

34. If 30g of lead iodine is produced calculate
the percentage yield.
Why might the yield be less than 100%?
34.8g is the predicted grade
30g is the actual grade
30 x 100%
34.8
= 86.2%

35. K has an atomic number of 19. Draw its electron
structure and state which period and group it is in.
Give reasons for your answer.
4 shells so period 4
1 electron in outer shell so group 1

36. S t r e t c h q u e s t i o n
Barium chloride and sodium sulphate are mixed. A precipitate of
barium sulphate and sodium chloride is formed.
Balance the equation for this reaction
BaCl2(aq) + Na2SO4 (aq) ------> BaSO4(s) + NaCl(aq)2

37. The (aq) symbol means aqueous. What does this mean?
The barium chloride is in solution

38. Find the Mr for each of the substances.
The Ar of Pb = 207
The Ar of K = 39
The Ar of I = 127
The Ar of N = 14
The Ar of O= 16
Pb(NO3)2 + 2KI → PbI2 + KNO3
207 + (14+3 x 16) x 2
331
39 + 127
166
207 + 2 x 127
461
39 + 14+ 16 x 3
101

39. What percentage of Iodine is there in lead iodine?
Pb(NO3)2 + 2KI → PbI2 + KNO3
How much would 1 mol of lead nitrate weigh?
331 166 461 101
Out of the 461 iodine is 2 x 127 so
127 x 2 x 100 = 55.1%
461
Mr = 331 so 331 g

40. 25 g of lead nitrate is reacted to produce the lead
iodine. How much lead iodine will be produced?
Pb(NO3)2 + 2KI → PbI2 + KNO3
331 166 461 101
331g would produce 461g
1g would produce 461/ 331
25g would produce (461/ 331) x 25 g
= 34.8g

41. If 30g of lead iodine is produced calculate
the percentage yield.
Why might the yield be less than 100%?
34.8g is the predicted grade
30g is the actual grade
30 x 100%
34.8
= 86.2%

42. A bee sting is acidic
A wasp sting is alkaline
What everyday substances could be used to
treat each of the stings?

43. Barium chloride and sodium sulphate are mixed.
A precipitate of barium sulphate and sodium chloride is formed.
Balance the equation for this reaction
BaCl2(aq) + Na2SO4 (aq) ------> BaSO4(s) + NaCl(aq)

44. The (aq) symbol means aqueous. What does this
mean?
Name the two reactants in the reaction
Name the two products in the reaction
Barium sulphate is a precipitate – what does the
term precipitate mean?
In solution
Barium chloride and sodium sulphate
A solid forms
barium sulphate and sodium chloride

45. Use the following information to answer the next question
Ar of Ba = 137 Ar of S = 32
Ar of Cl = 35.5 Ar of O = 16
Find the formula mass of each of these compounds involved in the reaction.
BaCl2 BaSO4
What is percentage of barium is in (a) barium chloride and (b) barium sulfate
How much would 1 mol of barium chloride weigh?
What is the mass of one mole of barium chloride?
30 g of barium sulphate is reacted in an excess of sodium sulphate to
produce barium sulphate. How much barium sulphate will be produced?
If 32 g of barium sulphate is produced calculate the percentage yield.
208 233
65.9% 58.8%
208g
233g
233/ 208 x 30 = 33.6g
32/33.6 x 100 = 95.2%