Unit 5 Flashcards
(81 cards)
1
Q
(a) When metals burn in air or oxygen what type of compound is made?
(b) Be able to write balanced equations for metals burning in air e.g.
i) sodium and ii) calcium burning in air.
A
Metal Oxide
i) 4Na + O2 → 2Na2O
ii) 2Ca + O2 → 2CaO
2
Q
What type of solution (acid/alkali/neutral) do metal oxides that dissolve in water tend to produce?
A
Alkali
3
Q
- Do all metal oxides dissolve in water?
A
No (check Data Booklet)
4
Q
(a) Where can you find out if metal oxides dissolve in water?
(b) Write the names of 2 metal oxides that dissolve in water and 2 that do not.
(c) Give the names of the products for the 2 metal oxides that do dissolve.
A
a) Page 8 of the Data Booklet
b) Do dissolve: Sodium Oxide, Potassium Oxide
Don’t dissolve: Copper Oxide, Aluminium Oxide
c) Sodium Hydroxide, Potassium Hydroxide
5
Q
(a) When non-metals burn in air or oxygen what type of compound is made?
(b) Be able to write balanced equations for non-metal elements burning in air e.g.
(i) sulfur and (ii) carbon burning in air.
A
Non-Metal Oxides
i) S + O2 → SO2
ii) C + O2 → CO2
6
Q
What type of solution (acid/alkali/neutral) do non-metal oxides that dissolve in water tend to produce?
A
Acidic
6
Q
(a) What type of oxide (acid/alkaline/neutral) would phosphorus produce?
(b) What type of oxide would hydrogen produce?
(c) what type of solution do metal hydroxides that dissolve in water produce?
A
A) Acidic
B) Neutral (makes water!)
C) Alkaline
7
Q
(a) What is required to enable nitrogen to react with oxygen?
(b) Name the oxide produced.
(c) Which acid is made when this oxide dissolves in water?
A
a) Large amount of electrical energy (sparks)
b) Nitrogen Dioxide
c) Nitric Acid
8
Q
The pH scale is continuous from below ______ to above _______ .
A
0 to 14
8
Q
What type of solution has a pH less than 7?
A
Acidic
9
Q
- What type of solution has a pH more than 7.
A
Alkaline
10
Q
- What pH do pure water and neutral solutions have?
A
7
10
Q
- What type of solution is formed when ammonia dissolves in water?
A
Alkaline
10
Q
- Name 2 common acids and alkalis in use at home and in the laboratory.
A
Acids: Hydrochloric Acid, Sulphuric Acid
Alkali: Sodium Hydroxide, Potassium Hydroxide
11
Q
- Why do acids conduct electricity? Explain
A
When dissolved in water they dissociate into ions. Ions are charged particles and will be free to move
12
Q
- Which type of bonding do acids have?
A
Covalent
13
Q
- Do alkalis conduct electricity? Explain
A
Yes, alkalis are ionic and when dissolved in water, ions are free to move
14
Q
- What type of bonding do alkalis have?
A
Ionic
14
Q
- Which ion is present in all acid solutions?
A
H+
14
Q
- Which gas is always produced at the negative electrode when acids are electrolysed?
A
Hydrogen
15
Q
- Which ion is present in all alkaline solutions (alkalis)?
A
OH-
16
Q
. In water and neutral solutions, how do the concentrations of hydrogen ions
and hydroxide ions compare?
A
The concentrations are equal
17
Q
(a) How do the concentrations of hydrogen ions and hydroxide ions compare in an acidic solution?
(b) How do the concentrations of hydrogen ions and hydroxide ions compare in an alkaline solution?
A
A) There is a higher concentration of H+ than OH- ions in acids
B) There is a higher concentration of OH- than H+ ions in alkalis
17
Q
What happens to the concentration of hydrogen ions if an acid is diluted?
What happens to the pH?
A
The concentration of H+ ions will decrease and so the pH will increase, moving towards 7
17
What happens to the concentration of hydroxide ions if an alkali is diluted?
What happens to the pH?
The concentration of OH- ions will decrease and so the pH will decrease, moving towards 7
17
(a) How well does pure water conduct electricity?
Explain your answer using the term “equilibrium”.
It conducts but poorly. Water dissociates into hydrogen and hydroxide ions but the reaction is in equilibrium, as water dissociates, the H+ and OH- combine to form water again
17
27. Write ionic formulae for hydrochloric acid and sulfuric acid.
Hydrochloric acid: H+(aq) + Cl-(aq)
Sulfuric acid: 2H+(aq) + SO42-(aq)
18
29. What are the units of concentration?
mol l-1
18
28. Write ionic formulae for solid potassium hydroxide and solid magnesium hydroxide.
Potassium hydroxide: K+OH-(s)
Magnesium hydroxide: Mg2+(OH-)2
18
Write the triangle relating the number of moles, volume and concentration.
n = cv
| n = num of moles
c = concentration
v = volume (litres)
19
Calculate either the number of moles of solute, the volume or concentration of a solution given the other two pieces of information.
e.g. (a) Calculate no of moles in 25cm3 of a solution of 0.25 mol l-1
(b) Calculate volume of a 0.5 mol l-1 solution that contains 0.2 moles
(c) Calculate the concentration of a solution containing 25 moles made up to 5000 cm3.
(a) n = v x c = 0.025 x 0.25 = 0.00625 moles
(b) v = n/c = 0.2/0.5 = 0.4 litres
(c) c = n/v = 25/5 = 5 mol l-1
20
32. Describe the difference between a concentrated solution and a dilute solution.
concentrated = large quantity of dissolved solute, small quantity of water
dilute = small quantity of dissolved solute, large quantity of water
N.B. A solute is usually a solid but can be a gas or a liquid which is less common.
21
33. How does concentration affect the conductivity of an ionic solution?
The higher the concentration the higher the conductivity
22
Name the gas produced when a metal
reacts with acid.
Hydrogen
23
Complete the word equation
metal + acid ->
metal + acid -> metal salt + hydrogen
24
Write word and balanced equations for reactions between metals and acid e.g.
(i) magnesium + sulfuric acid,
(ii) iron + hydrochloric acid
(Assume that the valency of iron is 2.)
magnesium + sulfuric acid 🖉 magnesium sulfate +
(i) H2 Mg + H2SO4 🖉 MgSO4 + H2
(ii) iron + hydrochloric acid🖉 iron chloride + H2 Fe + 2HCl 🖉 FeCl2 + H2
25
4. Name 3 metals that do not react with acids. (There is one in particular that you MUST remember!)
Silver, gold – obvious ones plus copper, which you must remember.
26
5. In the reaction with metals, what happens to the hydrogen ions from the acid?
H+ ions react forming H2 gas
27
6. What is the test for hydrogen gas?
Burns with a pop
28
7. Write the definition of a salt.
A compound made from an acid where the H+ ions have been replaced by metal ions (or the ammonium ion)
29
8. What is the name ending of the salts produced from
(i) hydrochloric acid
(ii) sulfuric acid
(iii) nitric acid?
(i) chloride
(ii) sulfate
(iii) nitrate
30
9. Write ionic formulae for (i) hydrochloric acid (ii) sulfuric acid (iii) nitric acid
(i) H +(aq) + Cl-(aq)
(ii) 2H+(aq) + SO42-(aq)
(iii) H+(aq) + NO3-(aq)
31
10. Write the full ionic equations for the reactions in 3 above. Remember state symbols
(i) Mg(s) + 2H+(aq) + SO42-(aq) → Mg2+ (aq) + SO42-(aq) + H2(g)
(ii) Fe(s) + 2H+(aq) + 2Cl-(aq) → Fe2+ (aq) + 2Cl-(aq) + H2(g)
32
Identify the spectator ions in the 2 ionic equations above.
(i) SO42-(aq)
(ii) 2Cl-(aq)
33
12. Write the ionic equations omitting spectator ions for the reactions above.
(i) Mg(s) + 2H+(aq) → Mg2+ (aq) + H2(g)
(ii) Fe(s) + 2H+(aq) → Fe2+ (aq) + H2(g)
34
13. Is the reaction of metals and acids a neutralisation reaction? Explain your answer.
No, because water is not produced in the reaction
35
Complete the word equation:
metal oxide + acid 🡪
metal oxide + acid → metal salt + water
36
Write word and balanced equations for reactions between metal oxides and acid e.g.
(i) magnesium oxide + sulfuric acid,
(ii) iron(III) oxide + nitric acid
magnesium oxide + sulfuric acid → magnesium
sulfate + water
MgO + H2SO4 → MgSO4 + H2O
iron(III) oxide + nitric acid → iron(III) nitrate + water
Fe2O3 + 6HNO3 → 2Fe(NO3)3 + 3H2O
37
16. Write full balanced ionic equations for the reactions in 2 above.
(i) Mg2+O2-(s) + 2H+(aq) + SO42-(aq) → Mg2+ (aq) + SO42-(aq) + H2O(l)
(ii) (Fe3+)2(O2-)3(s) + 6H+(aq) + 6NO3-(aq) → 2Fe3+ (aq) + 6NO3-(aq) + 3H2O(l)
38
17. Identify the spectator ions in the 2 ionic equations above.
(i) Mg2+ (even if the ions start and end in different states they are still the same ion so nothing has happened to the ion) and SO42-(aq)
(ii) Fe3+ and NO3-(aq)
39
18. Write the ionic equations omitting spectator ions for the reactions above.
(i) O2-(s) + 2H+(aq) → H2O(l)
(ii) O2-(s) + 2H+(aq) → H2O(l)
40
19. Why do all metal oxides and acids react in this way?
Because they are all reactions of O2- ions from the oxide with 2H+ ions from the acid forming H2O
41
Complete the word equation:
metal hydroxide + acid →
metal oxide + acid → metal salt + water
41
23. Write full balanced ionic equations for the reactions in 3 above.
(i) K+(aq) + OH-(aq) + H+(aq) + Cl-(aq) 🖉 K+(aq) + Cl-(aq) + H2O(l)
(ii) Ca2+(aq) + 2OH- (aq) + 2H+(aq) + SO42-(aq) 🖉 Ca2+ (aq) + SO42-(aq) + 2H2O(l)
42
21. What is another, more common name for metal hydroxides?
Alkalis
43
22. Write word and balanced equations for reactions between a metal hydroxide and an acid e.g.
(i) potassium hydroxide + sulfuric acid,
(ii) calcium hydroxide + hydrochloric acid
(i) Potassium hydroxide + sulfuric acid → potassium sulfate + water
(ii) Calcium hydroxide + hydrochloric acid → calcium chloride + water
Ca(OH)2 + 2HCl → CaCl2 + 2H2O
44
24. Identify the spectator ions in the 2 ionic equations above.
(i) K+(aq) and Cl-(aq)
(ii) Ca2+(aq) and SO42-(aq)
45
25. Write the ionic equations omitting spectator ions for the reactions above.
(i) 2OH- (aq) + 2H+(aq) → H2O(l)
(ii) 2OH- (aq) + 2H+(aq) → H2O(l)
46
Why do all metal hydroxides (alkalis) and acids react in this way?
Because they are all reactions of OH- ions from the hydroxide (alkali) with H+ ions from the acid forming water
46
Write word and balanced equations for reactions between metal carbonates and acid e.g.
(i) potassium carbonate + sulfuric acid,
(ii) calcium carbonate + nitric acid
(i) potassium carbonate + sulfuric acid → potassium sulfate + water + carbon dioxide
K2CO3 + H2SO4 → K2SO4 + H2O + CO2
(ii) calcium carbonate + nitric acid → calcium nitrate + water + carbon dioxide
CaCO3 + 2HNO3 → Ca(NO3)2 + H2O + CO2
46
29. Write full balanced ionic equations for the reactions in 2 above.
(i) 2K+(aq) + CO32-(aq) + 2H+(aq) + SO42-(aq) → 2K+(aq) + SO42-(aq) + H2O(l) + CO2(g)
(ii) Ca2+CO32-(s) + 2H+(aq) + 2NO3-(aq) → Ca2+ (aq) + 2NO3-(aq) + H2O(l) + CO2(g)
47
Complete the word equation:
metal carbonate + acid + →
metal carbonate + acid → metal salt + water + carbon dioxide
48
34. Write a definition of neutralisation.
The reaction of an acid with a base producing water.
48
30. Identify the spectator ions in the 2 ionic equations above.
(i) SO42- and 2K+
(ii) Ca2+ and 2NO3-
48
31. Why do all metal carbonates and acids react in this way?
It is always the CO32-ions from the metal carbonate that react with the H+ ions from the acid to form CO2(g)
48
32. What type of compound is always made when a metal, metal oxide, metal carbonate or metal hydroxide reacts with acids?
Metal salts (or just salts)
49
33. Write a definition for a salt.
A compound made from an acid where the H+ ions have been replaced by metal ions (or the ammonium ion)
49
Titration results were noted as follows all in cm3:
(i) 18.6 (ii) 18.3 (iii) 18.4
Calculate the average titre.
Average titre = 18.3 + 18.4 = 36.7/2 = 18.35 cm3
50
35. What is a base?
Metal oxides, metal carbonates and metal hydroxide (alkalis) N.B. NOT metals!
50
36. What is the common feature of all reactions when an acid is neutralised by a base?
The H+ ions of the acid reacts with the base forming water.
51
37. What are bases that dissolve in water called?
Alkalis
52
What happens to the pH of an acid during neutralisation?
Increases towards 7
53
Decide which chemicals you would use to prepare the following salts:
(i) copper(II) nitrate
(ii) magnesium sulphate
(iii) nickel chloride
(iv) sodium chloride
(i) nitric acid + copper(II) carbonate
(ii) sulfuric acid + magnesium carbonate
(iii) hydrochloric acid + nickel carbonate
(iv) sodium hydroxide + hydrochloric acid – with indicator to determine exact neutralisation
53
What happens to the pH of an alkali during neutralisation?
Decreases towards 7
54
Explain why using an insoluble metal carbonate is the easiest way to exactly neutralise an acid.
No heating is needed and when fizzing stops and an excess of the insoluble metal carbonate can be seen sitting at the bottom of the beaker then that means the acid has run out meaning that it all has all been neutralised. The excess carbonate can then be easily filtered off and the solution evaporated to get the solid salt.
54
Explain why using a soluble metal carbonate and an acid would not be a suitable method to make a solution of a metal salt.
There would be no excess visible to be sure that all the acid had been neutralised. Any excess would just dissolve in the water of the solution.
55
44. Write the triangle relating number of moles, volume and concentration.
n = cv
| n = num of moles
c = concentration
v = volume (litres)
55
42. Name 4 different everyday examples of neutralisation.
1. Stomach acid is neutralised by alkaline indigestion remedies.
2. Acid soil is neutralised by lime (calcium oxide), a base.
3. Acid rain in lochs is treated with limestone (calcium carbonate), a base.
4. Toothpaste is alkaline to neutralise acids in the mouth.
55
56
Calculate the volume of 0.5 moll-1 hydrochloric acid needed to neutralise
25cm3 of 0.2 moll-1 sodium hydroxide.
NaOH + HCl → NaCl + H2O
1 mol acid reacts with 1 mol alkali
Moles alkali = 0.025 x 0.2 = 0.005
Therefore moles acid also = 0.005
Volume = moles/conc = 0.005/0.5 = 0.01 litres = 10 cm3
57
47. Calculate the concentration of sulfuric acid used if 20.5cm3 of the acid neutralises 25cm3 of 0.2 moll-1 sodium hydroxide.
2NaOH + H2SO4 → Na2SO4 + 2H2O
2 mol alkali reacts with 1 mol acid
Moles alkali = 0.025 x 0.2 = 0.005
Therefore moles acid = half the moles of alkali =
0.005/2 = 0.0025
conc = moles/vol(l) = 0.0025/0.0205 = 0.12 moll-1
