Chemistry 3 (Practical) Answers.

NOTE: Tita means θ
^ means Raise to power
Pie means π
/ (means) division or divide
2 whole no 3/4 means 2¾
* means multiplication (×)
Sqr root means √
Proportional means ∝
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1) Tabulate Burette reading|Final burette reading (cm^3)|Initial burette reading (cm^3)| Volume of acid used(cm^3)| Rough- 24.10,0.00,24.10 First- 23.80, 0.00, 23.80 Second- 23.75, 0.00, 23.70 Third- 23.75, 0.00, 23.75 Average volume of A used = 23.80 23.70 23.75cm^3/3 =23.75cm^3
1bi) CAVA/CcVc=2/1 Cc=CAVA/2VC =0.100*23.75Moldm^-3/2*25.00 =0.0475moldm^-3 amount of A used = 0.100x VA/1000=0.100*23.75/1000 =0.00237 2moles Of A = 1mole of C 0.002375mol of A = 0.002375mol/2 100cm^3 of C contain 0.00237*100mol/2*25 =0 1000cm3ofCcontained0.002375x1000mol 2x25 =0.0475mol concentration of C in moldm-3 =0.0475moldm-3
1bii) Molar mass of Bing mol-1: Molar mass of Na2CO3.yH2O=mass concentration of Bingdm-3 molar concentration of Binmoldm-3 =13.6gdm-3 0.0475moldm-3 =286gmol-1
1biii) Molar mass of Na2CO3 =[(2×23) 12 (16×3)]=106gmol-1 Mass of anhydrous Na2CO3=106x0.0475gdm-3 =5.035gdm-3 Mass of water=13.6-5.035gdm-3 =8.565gdm-3 Mass of Na2CO3 =Molar mass of Na2CO3 Mass of water y×Molar mass of water 5.035=106 8.565 18y y =106x8.565 5.035x18 =10
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(2)Tabulate Test
(a)(i)Fn H2O,then filter
Observation White residue and blue filtrate was observed Inference Fn is a mixture of soluble and insoluble salts Test
(ii)Filtrate NaOH(aq)in drops,then in excess Observation A blue gelatinous precipitate which is insoluble in excess NaOH(aq)was formed Inference Cu2 present
Test
(iii)Filtrate NH3(aq)in drops,then in excess Observation A pale blue gelatinous precipitate was formed. The precipitate dissolves or is soluble in excess NH3(aq)to give a deep blue solution Inference Cu2 confirmed
Test
(iv)Filtrate dil.HNO3 AgNO3(aq) Observation No visible reaction White precipitate formed Inference Cl-present
Test
NH3(aq)in excess Observation Precipitatedissolvedin excessNH3(aq) Inference Cl-confirmed
2bi)First portion of residue NaOH(aq) in drops, then in excess Observation White powdery precipitate which is insoluble in excess NaOH(aq) Inference Ca2 present Test
2bii)Second portion of residue dil.HCl Observation Effervescence/bubbles; colourless, odourless gas evolved. Gas turns lime water milky and turns damp blue litmus paper red. Inference Gas is CO2 CO3^2- or HCO3- present
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3i) lime juice is acidic in nature and the colour of methyl orange in acidic medium is red
3ii) Iron(iii)chloride will be reduced to iro(ii) with yellow deposit of sulphur
3iii) The color of KM2O4 is decolorized because SO2(g) acts as a reducing agent.
3iv) Addition of ethanoic acid to KCO3 results to the liberation of a colorless and odorless gas CO2 which turns lime water milky

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