NECO Chemistry practical answers 2020
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Indicator used is methyl orange.
Volume of pipette used is 25cm³
Final burette reading cm³|23.50|23.00|23.00|33.00|
Initial burette reading cm³| 00|0.00|0.00|10.00|
Volume of acid used(cm³) |23.50|23.00|23.00|23.00|
Average volume of A used = 23.00+23.00+23.00/3 =23.00cm³
Equation for the reaction
Concentration of A in moldm³ =concentration in gldm³.
3.6g of A =500cm²
Xg of A will be = 10000³
Xg=3.65*1000/500 =36.5/5 =7.3gldm³
Molar Mass of A HCl=1+35.5=36.5
Concentration of A =7.3gldm³/36.5gldm³
Concentration of B in moldm³
concentration of A in moldm³ CA=0.20
Volume of used VA=23.00
Concentration of B in moldm³ CB=?
Volume of B used VB= 25.00
CAVA/CBVB = n(A)/n(B) =2/1
Molar mass of B in glmol
Concentration of B(moldm-³)= conc gldm³/molar mass
0.092 * molar mass =10.60gldm³
Molar mass =10.60gldm³/0.092
Relative atomic mass of X in X²CO³
TEST; C + 5cm³ of distilled water and shake thoroughly. Divide the solutions into three portions.
OBSERVATION; A pale green solution results
INFERENCE; salt is soluble
TEST; To the first portion add NaOH solution in drys
OBSERVATION; Dark green gelatinous was formed
INFERENCE; Fe²^+ present
TEST; then in excess
OBSERVATION; precipitate is insoluble
INFERENCE; Fe²^+ present
TEST; To the second portion add K3Fe(CN)6 solution
OBSERVATION; A dark blue precipitate formed
INFERENCE; Fe²^+ confirmed
TEST; To the third portion add AgNO³ solution
OBSERVATION; White Precipitate formed
INFERENCE; SO4²^- , CL^- CO²^- present
TEST; To the results obtained in add dilute HNO3 in drops , then excess
OBSERVATION; White Precipitate is insoluble
INFERENCE; CL^- present
TEST; To the results obtained in add NH3 solution
OBSERVATION; White Precipitate dissolves
INFERENCE; CL^- Confirmed
I. Methyl Orange
II. Methyl orange
A white Precipitate is observed. Effervescence occurs a gas is evolved which change lime water milky.
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Pls sir having chemistry practical February 3rd 2021 any idea on the questions will it be the previous question or a different one entirely
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