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WAEC 2018 Chemistry Practical Expo Answer | WAEC Chemistry Practical Expo Answer Solutions 2018/2019

57605410 349018 WAEC 2018 Chemistry Practical Expo Answer | WAEC Chemistry Practical Expo Answer Solutions 2018/2019

1 a )
Volume of pepette = 25. 00Cm ^ 2
Indicator Used = Methyl Orange

1 a )
Volume of pepette = 25. 00Cm ^ 2
Tabulate

BURETTE READING | ROUGH | 1 ST| 2 ND | 3 RD |
Final reading Cm ^ 3 | 25. 00| 34. 00| 29. 20| 24. 10|
Initial Reading Cm ^ 3 | 0 . 00| 10. 00| 5 . 00| 0 . 00|
Volume Of Acid Used In Cm ^ 3 | 25. 00| 24. 00| 24. 20|24. 10|

Average Volume of Acid used =( 24. 00+ 24. 20+ 24. 10/ 3 ) cm^ 3
= 24. 10cm^ 3

1 bi)
Con in mol/ dm 3 = conc in g / dm ^ 3 / molar mass
con of B in g / dm ^ 3 = 4 . 80/ 0 . 25 = 19. 2 g / dm ^ 3
molar mass = Fe + 2 Cl = 56+ 2 ( 35. 5 )=127 g / mol
conc in mol/ dm ^ 3 = 19. 2 / 127 = 0 . 15mol/ dm ^ 3

1 bii )
using CAVA / CBVB = NA / NB
CA* 11. 80/ 0 . 15* 20= 1 / 5
CA= 0 . 15* 20* 1 / 11. 80* 5
CA= 0 . 05moldm ^ – 3

1 biii)
mole = con ( mol/ dm ^ 3 ) x vol ( dm ^ 3 )
= 0 . 15* 20/ 1000
= 0 . 003 moles

============================

3a)
A white precipitate of barium sulphate will be
formed by the instant reaction between
sulphuric acid and barium chloride.
H2SO4(aq) + BaCl2(aq) -> BASO4 + 2HCl
(3b)
Iron II sulphide reacts with hydrochloric acid,
releasing the malodorous and very toxic gas,
hydrogen sulphide
FeS(aq) + 2HCl -> Fecl2(aq) + H2S(g)
(3c)
When solid iron fillings are added to dilute
aqueous hydrochloric acid, Iron(II)Chloride OR
ferrous chloride is formed, with the liberation of
hydrogen gas.
Fe(s) + 2HCL(aq) -> Fecl2 + H2(g)
[10:46, 4/3/2018] +234 903 517 2876: Pls Use Your School End Point .

Updated: April 3, 2018 — 10:52 pm

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