KAMUKUNJI DISTRICT KCSE EVALUATION TEST
CHEMISTRY PAPER 1
233/1,
MARKING SCHEME
1. (a)Pipette
Burette
Volumetric flasks
Syringe
any 2 correct (1mk)
(b) Glass is transparent hence one can see through easily
Glass does not react with most chemicals.
2. (a) x-2.8.2
(1mk)
Y-2.8.7
(b) Atomic radii of x is larger than that of y (1mk)
(C) Alkaline earth metals
3. (i) backward reaction would be favoured/equilibrium shift to the left because backward
1
reaction is endothermic and is favored by an increase in temperature(12mks)
(ii) SO2g +O2 g
2SO3g
Forward reaction would be favored because it has fewer molecules.(1.5mks)
4. Add excess dilute nitric (v) acid to the given calcium oxide
Calcium nitrate is formed.
Add sodium carbonate solution // k2co3aq//NH4CO3aq to the calcium nitrate solution formed
Filter to obtain caco3 as residue
percentages
moles
Simple ratio
Fe
20.2
20.2
56
0.3607
1
KAMUKUNJI DISTRICT KCSE EVALUATION TEST 2014
(3mks)
S
11.5
O
23
H2O
45.3
23
16
11.5
32
0.359
1
1.438
4
1
45.3
18
2.517
7
Formula is FeSO4.7H2O
6. (a) AB3
(3mks)
(1mk)
(b)
(1mk)
7. (a) hydrogen gas(1mk)
(b) To increase the surface area for absorption of hydrogen chloride gas in water(1mk)
(c) Manufacture of dyes, drugs, photographic materials
A common laboratory reagent used in schools and in researched institutions
8. (a) maximum number of grams of solute that dissolves in 100g of water to form a saturated
solution (1mk)
(b) 8g=20g
?
=100g
8×100
20
=40g per 100g water (2mks)
9. (a) 22.4 dm3 of CO2 are occupied by = 1 mole

20 dm3 of CO2will be occupied by =20*1 moles1/2
22.4
= 0.89286 moles
No of moles of C6H12O6 = 1/2 no moles of CO2
= ½ x 0.89286
= 0.44643 moles1/2
RMM(C6H12O6) ) = 6X12+12X1+6X16
= 1801/2
KAMUKUNJI DISTRICT KCSE EVALUATION TEST 2014
2
Mass of C6H12O6 ) = 180x 0.44643
= 80.3574 g 1/2
(b) Zymase1
10.(a) x beta particles
Y
alpha particles
(b) Gamma radiation (2mks)
EØ=-0.76--2.37
=2.37-0.76
=+1.61v (1mk)
ii Mg(s) +Zn2+
11.(a) i
(b)KNO3
Mg2+ aq +Zn(s)(1mk)
+//KCl//NaNO3//NaCl (1mk)
12.(a) – bursts into alilac flame
- Darts on the surface of the water
- produces a hissing sound
- floats (2mks)
(b) 2 K(s) +2 H2O(l)
2KOH(aq) + H2(g)(1mk)
13. (a)Haematite Fe2O3 or Magnetite Fe3O4(1mk)
(b) Silicon (IV) oxide (silica)
Aluminium oxide (2mks)
(c) Hydrated iron (III) oxide (1mk)
14.(a) z- has high M.p and B.p and is a good conductor of electricity(1.5mks)
(b) x- has high M.p and B.p and is poor conductor of electricity (1.5mks)
15. (a) the heat change occurs when one mole of a substance dissolves in a solvent to form an
infinitely dilute solution.(1mk)
(b) Change in temp= 22-20=20c
80
Enthalpy change=1000×4.2kgk-1×2k
=0.672kj.
m.m of NH4NO3=28+4+48=80g
KAMUKUNJI DISTRICT KCSE EVALUATION TEST 2014
3
2
Moles= 80=0.025 moles
0.025 moles produces 0.672
1mole=?
1 × 0.672
0.025
= 26.88kj/mol(3mks)
16.(a) yellow solid deposited(1mk)
(b) H2S aq+ Cl2g
2HClg + Ss
Hydrogen sulphide is the reducing agent (2mks)
17. Zn CO3(s) + 2 HNO3 (aq)
Z n (NO3)2(aq) + CO2 (g) + H2O (l)
4moles= 1000cm3
?= 50cm3
4×50
1000
=0.2 moles
Moles of HNO3 reacting are 0.2 moles
Moles of zinc carbonate reacting are 0.1 moles.
Mass of ZnCO3=125g×0.1=12.5g
Mass of ZnCO3 unreacted is 17-12.5=4.5g (3mks)
1
18.(a) volume is inversely proportional to pressure(p∝ 𝑣)
(b)
𝑝1×𝑣1 𝑝2×𝑣2
𝑡1
=
𝑡2
P1=750mmhg
V1=600cm3
T1=273-23=250k
P2=900
V2=?
KAMUKUNJI DISTRICT KCSE EVALUATION TEST 2014
4
T2=306k
V2=
750×600×306
250×900
=612cm3(3mks)
19. (a) (i) Zinc(1mks)
(ii) Hydrogen gas (1mk)
(b)(Zn (NH4)3)2+ (1mk)
20. Na2SO3 (aq) + 2HClaq
2NaCl (aq) + SO2 + H2O (l)(1mk)
(b) To increase surface area of dissolving and hence prevent sucking back of water because the
gas is very soluble.(1mk)
(c) lowers the PH because the gas is acidic.(1mk)
21. (a) iron ( II) sulphide(1mk)
(b) Hydrogen sulphide(1mk)
22.3C + 4 H2
C3H8
3CO2 (g) +4H2O (l)
-393× 3 + 4 × −286 = 𝐷𝐻𝑓 + −2220
-1179-1144+2220=DHf
-2323+2220=DHf
-103=DHf
DHf(C3H8)= -103kj/mol(3mks)
23. (a) cracking(1mk)
(b) propene(1mk)
(c) C3H8 (g) +5O2g
3CO2g +4H2O l(1mk)
24. Fractional crystallization (1mk)
(b) Making health drinks/ baking powder (1mk)
25. Ethyne// hydrogen (1mk)
KAMUKUNJI DISTRICT KCSE EVALUATION TEST 2014
5
26. Aluminium is a better electrical conductor than sodium because aluminium has more
delocalized electrons in its structure.(1mk)
27.(a) hydroxide ion(1mk)
(b) (i) B,A,C(1mk)
(ii) Group I(1mk)
28. (a) black copper (II) oxide turns brown
- Lime water forms a white ppt(1mk)
(b) C uO(s) + CO (g)
CuS + CO2 (g)
29.(i) 2// 3(1mk)
(ii) 1 and 5(1mk)
30. (a) brown solids dissolves
Blue solution is formed
Brown gas is evolved (any 2 correct 1mk)
(b) conc. nitric (v) acid is an oxidizing agent and oxidizes copper metal to blue solution copper
(II) nitrates while itself is reduced to brown nitrogen (IV) oxide.(1mk)
KAMUKUNJI DISTRICT KCSE EVALUATION TEST 2014
6