The temperature at which substance change from solid to liquid
1
1
0
(b)
Q2 C
1
1
(c)
Solid + Liquid
1
1
(d)
Heat energy is absorbed absorbed to overcome the force of attraction between particles
1 1
2
1
1
(e)
(f)(i) 1. Both axis are labeled and with correct unit 2. Correct shape of the curve and mark Q2
1 1
2
o
Temperature ( C) o Suhu ( C)
Q2
t2
t1 (ii)
Time(s) Masa(s)
Liquid X should be be stirred continuously continuously during cooling // the boiling tube containing liquid X should be placed inside the conical flask.
Total
1
1
9
1
4541/2 Scheme
Question No 2 (a)
SULIT
Explanation
Mark
∑Mark
1
1
1
(b)
C
1
(c )
Atomic size E smaller than D//The number of proton in atom E more than atom D The force of attraction between proton and electron of atom E stronger Easier for atom E to accept electron
1
(d) (i)
4A + B2 2A2B Correct formula of reactant and product Balanced
1 1
3
1 1
2
(ii)
High melting/boiling point //can conduct electricity in molten state or aqueous solution // soluble in water.
1
1
(e)
Show different oxidation number // form coloured ion/compound //act as catalyst // form complex ion
1
1
TOTAL
9
2
4541/2 Scheme
SULIT
No.
Answer
Sub Mark
Mark
3 (a) (b)
1 1 1 1
1
(c)
Ionic bond (i) 2.8.2 (ii) 2.8.7 7
(d)(i)
CY4 //CCl4
1
1
1. Nucleus for both both atoms are label & all shells filled with correct number of electrons. 2. Sharing one pair of electrons
1
(ii)
2 1
2 1
Y
Y
Y
C
Y
(e)
1. Melting point of compound Diagram Diagram 4 / XY2 is higher 2. Electrostatic forces between particles/ ions is stronger str onger 3. More heat/energy required to overcome the forces
1 1 1 3
Total
10
No. 4
(a) (b)
(i)
Answer
Mark
Formula that show the simplest whole number ratio of atoms of each element in the compound
1
Sample answer Zinc and hydrochloric acid
(ii)
1
Zn + 2HCl ZnCl2 + H2 - correct formula for reactants and products - balance the equation 2
(c)
The air in the combustion tube must be displaced before lighting the hydrogen gas
3
1
4541/2 Scheme
(d)
SULIT
(i) Element Mass Number of mole
X 0.64 g
O 0.16 g
0.64
0.16
0.01
64
Simplest ratio
1
1 0.01
1
16
1 1
Empirical formula is XO (ii)
XO + H2 X + H2O - correct formula for reactants 2
- correct formula for products Total
No.
Answer
5(a)
10
Sub Mark
Mark
Cl and OH
1
1
Colourless gas bubbles
1
1
(ii)
Oxygen
1
1
(iii)
Insert a glowing splinter into the test tube. t ube. The glowing splinter rekindles.
1 1
2
(c)(i)
Copper
1
1
Correct formulae of reactant and product
1
-
(b)(i)
(ii)
-
2+
Cu (d)(i)
2 Cl
(iii)
→
Cu
Correct formulae of reactant and product -
(ii)
1 + 2e
1 →
Cl2 + 2e
1
Chlorine
1
1. Cl- ion donate / loss 1 electron to form chlorine atom 2. Two chlorine atoms combine to form chlorine molecule/ gas
Total
1
1 1
2 11
4
4541/2 Scheme 6
SULIT
(a)
conical flask
1
(b)
neutralisation
1
(c)
(i)
Titration
1
(ii)
pink to colourless
1
(i)
NaOH + HCl→ NaCl + H 2O
1
(ii)
sodium chloride
1
(d)
(e)
No. of moles of NaOH = 25 x 1.0 // 0.025 mol 1000 1 mol NaOH react with 1 mol HCl // 0.025 mol NaOH react with 0.025 mol HCl 3
Volume of HCl HCl = 1000 x 0.025 cm // 25 cm 1.0
1
1 3
1
Or VHCl = 1 x 1.0 x 25 1 1.0 = 25 cm
(f)
1+1
3
1
Sulphuric acid is a diprotic acid // hidrochloric acid is a monoprotic acid + produce same concentration of H ion
5
1 1 11
4541/2 Scheme 7
(a)
SULIT
(i) Electrod Q. Mark from negative battery to cathode // from anode to positive battery. (ii)Electrode P: Concentration of ions in the electrolyte. Electrode Q: Position of ion in the electrochemical series. (iii) Electrode P: iodine molecule//iodine Electrode Q: hydrogen molecule/gas//hydrogen P:
-
2I
1 1 1 1 1 1
I2 + 2e
1
Q: 2H + 2e H2 Confirmatory test at P: - Starch solution is added into the solution around electrode P , -blue colouration / precipitate is formed
1
+
1 1
(b) Cell X Type of cell Electrolytic cell The energy change Electrical energy to chemical energy The terminal of Positive terminal the cell / anode: Copper
Cell Y Voltaic cell Chemical energy to electrical energy
1 1
Positive terminal / cathode: copper 1
Ions present in the electrolyte Observation
Negative terminal / cathode: copper 2+ + Cu , H 2SO4 , OH Anode: Thinner
Negative terminal / anode: aluminium 1
1
Negative terminal/Aluminium plate: thinner
1
Half equation for both electrodes
Cathode: brown deposit//brown solid is deposited//thicker
Positive terminal/Copper plate: brown deposit//brown solid is deposited//thicker
Anode: 2+ Cu Cu + 2e
Al plate/- terminal: 3+ Al Al + 3e
Cathode: 2+ Cu +2e
Cu plate//+ terminal: 2+ Cu +2e
Cu
1
1+1
1+1 Cu max 10 Total
6
20
4541/2 Scheme
SULIT
No.
Answer
Sub Mark
Mark
8 (a)(i)
Oleum
1
1
1. Moles of sulphur = 48 / 32 =1.5
1
2. 1 moles moles of sulphur produce 1 moles of SO2 // 1.5 moles of sulphur produce 1.5 moles of SO2
1
(ii)
3. Volume of SO2 = 1.5
(iii)
(iv)
3
3
3
24 dm // 36 dm
1. Catalyst: Vanadium (V) oxide // V2O5 o 2. Temperature: 450 - 500 C 3. Pressure: 1 atm
1 1 1 1
(NH4)2SO4
1
Urea
1
% of nitrogen in ammonium nitrate = 2 x 14 x 100 % 80 % of nitrogen in urea = 2 x 14 x 100 % 60
(b)(i) (ii)
(iii)
(iv)
// 35%
1
// 46.7 %
4
the percentage of nitrogen by mass of urea is higher Polymer is a long chain / big molecules made up of many repeating units / monomer PVC
3
1 1
1
1+1
2
1 1 1 1
4
1 1
2
Chloroethene H
H
C
C
H
Cl
H
H C
n
H
C Cl
1. 2. 3. 4.
Polymer not easily biodegradable / decomposed by bacteria Block / clog up the t he drainage system // causing flash flood Burning of polymer will produce toxic gas Gas dissolved pollutes the lake / river and making the water not suitable for aquatic organism. 1. Reused, recycle and reduce 2. Heating the polymer without oxygen / pyrolysis Total
7
20
4541/2 Scheme Question No 9 (a)
SULIT
Explanation
Mark
∑Mark
Group 1, Period 2 one valence electron two shells occupied with electrons
1 1 1
3
Correct electron arrangement of 2 ions Correct charges and labeled
1 1
(b)
+
X
X
X
-
XX X X
X X
X XX
A
(c)
B
Electron arrangement of atom A is 2.1 to achieve octet electron arrangement + atom A donate 1 electron to form A
1 1 1
Electron arrangement of atom B is 2.7 Atom B accept 1 electron to form B + A ion and B ion are attracted to each other by a strong electrostatic force/ ionic bond
1 1
1. A crucible is filled with solid R until it is half full. 2. Two carbon electrodes are dipped in the solid R and connected connected to the batteries. 3. Switch is turned on and observation is recorded. 4. The solid R is then heated until it melts completely. 5. The switch is turned on again and observation is recorded. 6. Steps 1 to 5 are repeated using solid T to replace solid R. 7. Observations: R does not light up the bulb in both solid and molten states. T lights up the bulb in molten state only.
1
R: naphthalene // any suitable answer T: lead(II) bromide // any suitable answer
1
TOTAL
1
1 1 1 1 1 1
1 1
20
8
8
10
4541/2 Scheme
SULIT
No.
Answer
Sub Mark
10(a)(i)
Burette yellow
1 1
Mol of lead(II) ion = 5x1/1000 // 0.005
1
Mol of chromate(VI) ion = 5x1/1000 // 0.005 (ii)
2-
1 mol CrO4
2+
(iv) (b)(i) (ii)
(iii)
4
1 1
Ionic equation : Pb (iii)
Mark
+
2-
CrO4
→ PbCrO4
1
2
1. Add sulphuric acid and then follow by iron(II) sulphate solution 2. Slowly and carefully add concentrated sulphuric acid 3. Brown ring form indicate the presence of NO3- ion
1 1 1
Magnesium nitrate is a soluble salt // No precipitate is formed
1
3 2
Compound formed when hydrogen ion from an acid i s replaced by metal ions or ammonium ions
1
1
Silver chloride // AgCl
1
Double decomposition reaction
1
3
-3
1. Pour [50-100 cm ] [0.5-2.0 mol dm ] silver nitrate solution into 2. 3. 4. 5. 6. 7.
a beaker 3 -3 Add [50-100 cm ] [0.5-2.0 mol dm ] sodium chloride / any soluble salts solution contain chloride ions into i nto the beaker Stir the mixture Filter the mixture Rinse the residue with distilled water Dry the salt by pressing it between between filter papers Equation: +
