CONFIRM 2012 GCE CHEMISTRY OBJECTIVE AND THEORY ANSWERS

CHEMISTRY OBJECTIVE ANSWERS.

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CHEMISTRY THEORY ANSWERS.

(2a)
(i)?Boyle?s law state that the volume of a given mass of a gas is inversely proportional to the pressure . i.e V (alpha)1/p
(ii)?V (alpha)1/p
V= k/p, V1P1= V2P2
(iii)?(1) it occurs at high temperature (2) also at low pressure

(IV) (I) – gases are made up of molecules which are in constant random motion.
-?The particles do not attract each other
-?The total volume actually occupied by the gas molecule is negligible compared with the volume of the container
(II) Dalton law of partial pressure state that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressure of each constituent provided the gases would not chemical react together. i.e. PT= PA+ PB +PC+PD

(2b)(i) p – Condensation, Q- Freezing, R- sublimation
(ii) I- Sublimation, II- Iodine molecule
(2c) t1/t2= (square root of ) m1/m2
Rate of diffusion = vol/time
RCH4= 80/20=4?
RQ=50/25=2
RCH4/RQ= square root of) mQ/MRcH4
4/2=square root of) MQ/16
4/2= square root of) MQ/4
Square root of MQ= 4 x 4/2= 16/2=8

(8a)

k-metallic bond
H2-covalent bond
KH-covalent bond
units which make up the subsctance
k-kilojoule
H2-kilojoule
KH-kilojoule
(8bi) H20>H2>CH4
increasing order of boiling points
(8bii)
boiling points increase with the member of hydrogen bond

(8di) it reacts with base to form salt and water, it react with metall to form hydrogen gas
(8dii)
I-acidic
II–basic
III-acidic
Iv-acidic

1a)
(i) Q and S
(ii) R,S and U
(iii) (I) R and S
(II) U
(iv) T
(v) Q,R and S
(1b)
(i) electronegativity is the tendency of an element to withdraw electron towards itself
(ii) electronegativity increases across the period and decreases down the group
iii) atomic radius increases down the group due to the increasing number of shell fro the nucleus while it decreases across the period due to increasing clouds of electrons around the nucleus

1c)
(i) the form coloured ion
ii) they form complexes
iii) they exihibit paramagnetism
(1d)
i) 2KCLO3 =>2kcl + 3O2 (write MnO2 on top of the arow and little triangle below)
ii) MnO2 act as a catalyst
iii)the mass of chloride produced
moles = mass/ molar mass
M.m = (39 + 35.5) =74.5
KclO3=( 39 +35.5+3*16)= 122.5
moles of KCLO3 = 15/122.5=0.1225 moles
therefore, mass= 0.1225 * 74.5= 9.13 grams

(4ai) hybridization is the mixing or blending of two or more atomic orbitals to produce a new hybrid orbitals
(4aii) SP^2 and SP^3 hybridization are exhited by carbon atom in propene
(4aiii) (1) S-orbital is spherical, (2) P-orbital is dumb bell
(4B) electrons are not free in diamond and its held together by electostatic force of attraction whole in graphite, there are free electron
(4c) CnH2n+2=>alkane, RCL=>monochloroalkane

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