Neco gce chemistry practical answers 2017

1ai)
Methyl Orange
Reason – Titration of strong acid against base

(1aii)
Yellow

(1aiii)
Hydrochloric acid

(1aiv)2HCL(aq) x2Co3 -> 2 x CL(aq) H20(aq) CO2(g)

(1bi) Molar mass of HcL = 1 35.5
=36.5gmol^-1
Con of A is moldm^-3 =
Con of A of gdm^3/molar mass in gdm^3
=7.30gdm^-3/36.5gmol^-1
=0.200moldm^-3

(1bii)
using cava/cbvb =a/b

ca= 0.200mol/dm3
va=26.20cm3
cb=?
Vb=25.0cm3
a=2moles
b=1mole

0.200mol/dm3* 26.20cm3/Cb * 25.0cm3 = 2mol/1mole

cb = 0.200* 26.20*1/25.0*1
cb= 5.24/25.0 mold/dm3
cb= 0.2096mol/dm3

(1biii)
Conc. of B in gdm-3/Conc. of B in moldm-3
=10.6gdm-3/0.148 gdm-3
=101.15g
=101gmol-1

1biv)
Relative Molar Mass (RM)
X2CO3=101
(2*X)+12+(16*3)=101
2X+12+48=101
2X=101-60
2X=41
X=20.5=21
==================================

(2ai)
INFERENCE: Sample X is a soluble salt

(2aii)
OBSERVATION: A gas is evolved. The gas turns red moist litmus blue.
It forms white fumed when NaOH solution was added was added
INFERENCE: Alkaline gas

(2aiii)
INFERENCE: CO3 gas is CO3^2-

(2aiv)
INFERENCE: The solution is alkaline

BMASTERZ☆


(3a)
-NH4Cl and AgNo3
-ZnCo3
-FeS
-AgNO3
-NH4Cl

(3b)
-Burrette
-Retort stand
-Solution/Acid
-Conical flask

BMASTERZ☆