2016 Neco Chemistry answers Objectives and Essay

Chemistry- Answers-By - Lordeagle 1ai ) A mixture contains two or more constituents which can easily be seperated by physical methods 1aii ) magnesium trioxonitrate ( v ) = Mg ( NO 3) 2 molar mass of Mg ( NO 3) 2 =24 + 2 90 =24 + 2 62 =24 + 28 + 96 = 148 g/mol % of nitrogen = 2*24 *100/148 % of nitrogen = 48*100 /148 % of nitrogen = 4800 /148 % of nitrogen = 32. 43% 1aiii ) i) calcium oxide ( CaO) ii ) calcium choride ( CaCl2) 1bi ) CnH2n +1OH 1bii ) hydrolysation 1biii ) i) displacement reaction ii ) double decomposition reaction iii ) decomposition reaction iv) catalytic reaction v ) reversible reaction 1biv) i) endothermic heat change ii ) exothermic heat change 1ci) i) methyl orange ii ) phenolphthalein iii ) litmus 1cii) NH 4Cl+Ca( OH ) 2- -- - -> CaCl 2+2NH 3+2 H2O 1ciii ) it is collected by upward delivery 1civ ) mass of gas = 1.58 *22. 4 = 35. 392 vapour density = 35 .392 /1 relative molecular mass= V . D * 2 =35. 392*2 relative molecular mass= 70. 784

4b) - nitric oxide (NO) -nitrogen dioxide(NO2) - nitrogen pentoxide (NO5 ) 4b)(I) - nitric oxide (NO) -nitrogen dioxide(NO2) - nitrogen pentoxide (NO5 ) (ii) Charles’s law states that if a given quantity of gas is held at a constant pressure, its volume is directly proportional to the absolute temperature. (iii)...solution loading iv).... solution loading v). differences between thermoplastic and thermoset (Only two difference needed) ------ Thermoplastics can be melted and reshaped over and over again, while thermosetting plastics can only be heated and shaped once. ------thermoplastics­ has low melting points while thermoset has high melting point -----thermoplastic has low tensile strength while thermoset has high tensile strength 5a i) I - Carbon II Oxide and Hydrogen ii) II - Carbon II oxide,Nitrogen nd passing air over red hot coke in a furnace 5a (ii) Colloids are mixture in which are substance of micro scopically dispersed insoluble particles is suspended throughout another substances. Condensation is the change of the physical state of matter from gas phase into liquid phase. 5c (I) Vulanization is a chemical process for converting natural rubber or related polymer into more durable materials by adding sulphur or other accelerators. 5c(ii) Mass*Q M= IT t= mass/I =6.35/10.0 = 0.645 5c(ii) Polymer 4biii) CoH [H=1, C=12] 12*6 1*6 72 6= 78 12/78*100%=15.4% Dis ans is 4biv) CoH [H=1, C=12]12*6 1*672 6=78­12/78*100%=15.4% not 4biiii 6a)I)-Burning of Substances,for example wood,is a chemical change. burning Wood=========>ash ga­ses Ii)Addition of water to calcium oxide(quick lime) Cao(s) H20(l)=====>C­a(OH)2(aq)

6a i; the slaking of lime, the rusting of iron 6a ii)-Photosynthesis, -also absorbed by chemical alkalis. 6a111)6CO2(g) 6H2O(l) energy-->C6H12O6(aq) 6O2(g) 6aiv) It is unstable and decomposes to release oxygen which oxides the dye or stain thereby forming a colourless compound. 6bi)Two physical properties of ethene

1. Low melting and boiling point
2. Low density

Two physical properties of ethanol

1. Sharp smell
2. Colourless liquid

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Created at 2016-06-20

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