100% CORRECT NECO GCE(I) CHEMISTRY 2(OBJ & ESSAY) ANSWERS AVAILABLE HERE. Verified chemistry obj 1-10 EAECADAAED 11-20 ACACCBECCB 21-30 CECCEDEAAC 31-40 EDEABDCADD 41-50 AEEDBCDEED 51-60 CCDCEACCAA (3)(a) (i) -charge on the ion -postion of ion in the eletrochemical series -quality of electrolyte (ii) -extraction iof metals -purification of metals -electroplating (iii) Ag(+)+e(-)=>Ag 1 mole of electron will liberate 108g Q=It=2.6*20*60 96500C will liberate (108/96500) of Ag 3120C will liberate (10//96500)* (3120C) =3.49g of Ag (3b) (i) -presence of air -oxidation must take place (ii) rusting is the reaction of a substance with air while burning is the reaction of a substance with limited supply of oxygen (1) (a) (i) oxidation is defined as the loss of electrons in an atom (ii) HNO3 and Cl are oxiding agents. H2SO4 and CO are reducing agents (1b) (i) allotropy is the abilitiy of an element to exist in two or more form but in the same physical state (ii) -rhombic sulphur -monoclinic sulphur (1c) (i) oxygen=21% Nitrogen=78% carbon(iv) oxide=0.03% rare gases=1% (ii) HOCL=>CLO3+H20 oxochlorate (i) is formed (iii)1/2Cl2+1/2H20=>HOCL (iv) -chlorine is used to kill germs -chlorine is used as a blkeachiung agent (v) -natural gas -kerosine -gasoline -bitume (5) (a) (i)to kill germs (ii)to cause coagulation (iii) to allow for other particles to coagulate (5b) (i)-as a dehydrating agent -as a oxidizing agent -as a drying agen (ii)this is because concentrated tetra oxosulphate (vi) is corrosive and can cause serious burns (iii) Zn(s)+H2SO4(l)=>ZnSO4(s)+H2(g) (5c) (i)reversible reaction (ii) decreasing the temperature (iii) platinium (civ) Kc=9([NH3]^2/[N2][H2]^3) (5d) (i)the first law of thermodynamics states that in a chemical system, the net workdone on the system is equal to the net heat liberated in the system. (ii) valency of an element is defined as an ion with a charge which can be positive or negative (iii) conc in moldm^-3= mole/ volume volume=50/1000=0.05dm^3 0.5=mole/0.05 number of mole=0.5*0.05 =0.025mol molar mass=1+14+48=63gmol^-1 0.025=mass/63 mass of HNO3=0.025*63 =1.575g (5) (a) (i) to kill germs (ii) to cause coagulation (iii) to allow for other particles to coagulate (5b) (i) -as a dehydrating agent -as a oxidizing agent -as a drying agen (ii) this is because concentrated tetra oxosulphate (vi) is corrosive and can cause serious burns (iii) Zn(s)+H2SO4(l)=>ZnSO4(s)+H2(g) (5c) (i) reversible reaction (ii) decreasing the temperature (iii) platinium (civ) Kc=9([NH3]^2/[N2][H2]^3) (5d) (i) the first law of thermodynamics states that in a chemical system, the net workdone on the system is equal to the net heat liberated in the system. (ii) valency of an element is defined as an ion with a charge which can be positive or negative (iii) conc in moldm^-3= mole/volume volume=50/1000=0.05dm^3 0.5=mole/0.05 number of mole=0.5*0.05 =0.025mol molar mass=1+14+48=63gmol^-1 0.025=mass/63 mass of HNO3=0.025*63 =1.575g
Posted on: Tue, 12 Nov 2013 14:55:14 +0000
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