End of Section B Questions
1. a) (i) barium sulfate (1)
(ii) Ba
2+
(aq) + SO
4
2-
(aq) ----> BaSO
4
(s) (1)
b) Add sodium hydroxide solution (1) and look for blue precipitate (1).
c) (i) Brown precipitate (1). Solution fades from blue to colourless (1).
(ii) zinc (1). Loss of electrons (1).
d) (i) cathode (or negative) (1)
(ii) Cu
2+
(aq) + 2e
-
----> Cu(s) (1)
(iii) reduction (1). Gain of electrons (1).
2. a) (i) solid copper(II) oxide (or hydroxide or carbonate) (1)
(ii) sodium hydroxide (or carbonate) solution (1)
(iii) silver nitrate solution (1)
b) Add a measured volume of potassium hydroxide solution to a flask using a pipette (or
measuring cylinder) (1). Add a named indicator (1). Add acid from a burette (1) until a correctly
stated colour change (1). Note the volume of acid added (1). Mix the same volumes of acid and
potassium hydroxide solution without the indicator (1).
3. a) (i) A = chlorine (1)
(ii) B = hydrogen (1) (Allow one mark overall if reversed)
b) (i) bleaches (1) damp litmus paper (1)
(ii) pops (1) with lighted splint (1) (Consequential marking from part (a). e.g. If A
was mis-named as oxygen, allow a correct test for oxygen.)
c) (i) red / brown (1) solution (1) instead of colourless gas
(ii) no change (1)
d) copper(II) (1) bromide (1)
4. a) (i) Cl
2
(g) + 2I
-
(aq) ----> 2Cl
-
(aq) + I
2
(s) (1)
(ii) Colourless solution + green gas (1) gives dark grey precipitate (1) (allow red/brown
solution).
(iii) Oxidising agent (1) because it removes electrons (1) from the iodide ions.
b) (i) iron(II) (1) chloride (1)
(ii) I = iron(II) hydroxide (1). K = iron(III) hydroxide (1)
(iii) iron(III) chloride (1)
(iv) Fe
2+
(aq) + 2OH
-
(aq) ----> Fe(OH)
2
(s) (1)
5. a) Any sensible physical property (1) - e.g. solid rather than gas.
b) Correct reagent (e.g. water or oxygen or chlorine) (1). Name products (1). Correctly balanced
equation (2)
c) (i) Dots-and-crosses diagrams showing all the electrons: Na 2,8,1; K 2,8,8,1 (2 x 1 = 2)
(ii) Loss of outer electron (1)
(iii) Potassium's electron is further from nucleus (1) and so experiences less attraction (1).
Some mention of increased nuclear charge being offset by extra screening (1).
d) A molecule consisting of a single atom (1). Argon's outer level contains 8 electrons (1). No
room for sharing another electron to make the covalent bond needed to join other atoms to it. (1)
6. a) redox (1)
b) thermal decomposition (1)
c) neutralisation (1)
d) precipitation (1)
e) redox (1)
f) redox (1)