Chemistry Practical (Alternative B) Answers.

* NOTE THAT ^ MEANS Raise to power.*

Pls Draw Your Table As Usual And Input The Following : -

Volume of pipette = 25 . 00 cm ^ 3

indicator used- Methyl orange

colour change at end point - yellow to orange /purple

Note Use Your School End Point .

Tabulate
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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 . 75 cm ^ 3/ 3 =23 . 75 cm ^ 3

1bi) CAVA /CcVc = 2 /1 Cc= CAVA /2 VC =0 . 100* 23 . 75 Moldm ^ - 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 1000cm 3 ofCcontained 0 . 002375x 1000mol 2x 25 =0 . 0475mol concentration of C in moldm - 3 = 0 . 0475 moldm - 3

1bii ) Molar mass of Bing mol- 1 : Molar mass of Na2 CO 3. yH 2 O =mass concentration of Bingdm- 3 molar concentration of Binmoldm - 3 =13 . 6 gdm - 3 0. 0475 moldm- 3 =286gmol - 1

1biii ) Molar mass of Na2 CO 3 =[( 2 × 23 ) 12 ( 16 × 3)]= 106gmol - 1 Mass of anhydrous Na 2 CO3 = 106x 0 . 0475 gdm - 3 =5 . 035gdm - 3 Mass of water= 13 . 6 - 5 . 035gdm - 3 =8 . 565gdm - 3 Mass of Na 2 CO3 = Molar mass of Na2 CO 3 Mass of water y × Molar mass of water
5. 035= 106
8. 565 18 y
y =106x 8 . 565
5. 035x 18
=10
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2a ) Tabulate

Test
(i ) Fn H 2 O , 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 Cu 2 present
Test
(iii) Filtrate NH 3 (aq ) in drops , then in excess Observation A pale blue gelatinous precipitate was formed . The precipitate dissolves or is soluble in excess NH 3 (aq ) to give a deep blue solution Inference Cu 2 confirmed
Test
(iv ) Filtrate dil . HNO 3 AgNO 3( aq ) Observation No visible reaction White precipitate formed Inference Cl- present
Test
NH 3 (aq ) in excess Observation Precipitatedissolvedin excessNH 3 (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 Ca 2 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 CO 2 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 iron(ii) with yellow deposit of sulphur

3iii) The color of KM 2 O 4 is decolorized because SO 2 (g ) acts as a reducing agent.

3iv ) Addition of ethanoic acid to KCO 3 results to the liberation of a colorless and odorless gas CO 2 which turns lime water milky

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