PHYSICS SUBSCRIPTION

Neco 2018 PHYSICS Objective And Theory Questions And Answers Now Available With Us, Subscribe Now!

For Direct SMS It's: MTN ₦800
Whatsapp/Password: MTN ₦500

Send (i) Subject Name (e.g Physics) (ii) MTN Recharge Card Pin(s) (iii) Phone number to 08145912555

CLICK HERE FOR ANSWERS


Waec 2018 Chemistry Practical Answers – May/June Expo



We Posted Waec 2018 Chemistry Practical Answers For 2018 Waec Chemistry Practical May/June Expo, Free Waec 2018 Chemistry Practical Questions And Answers

ATTENTION:- ALWAYS SUBSCRIBE IF YOU WANT TO RECEIVE THE ANSWER FAST!

(1a)
Volume of pipette used=25.0cm^3
TABULATE
Reading: Rough|1st|2nd|3rd
Final reading: 16.00|15.40|17.20|15.30
Initial reading: 0.00|0.00 |2.00 |0.00
Vol of acid used: 16.00|15.40|15.20|15.30

B contains 4.80g/250cm³
Hence x8 = 1000cm³
X = 4.80 × 1000/250 = 4.80 × 4 = 19.2gdm³

(1bi)
Hence molar concentration of B in moldm3
Mass Conc(8dm³) = molar Conc × molar mass
Molar Conc of B = mass conc/molar mass = 19.2gdm³/127gmol
Cb = 0.151moldm3

(1bii)
Concentration of A in moldm-³, CA is given by CAVA/CBVB = na/nb
Where CA = ?
VA = 15.30cm³,
na = 1
CB = 1.51moldm-³, VB = 25.0cm³, nb = 5
CA × 15.30/0.151 × 250= 1/5
Therefore CA = 0.151×25×1/15.30×5 = 3.775/76.50 = 0.049moldm-³
Hence Conc. Of A in moldm-³ = 0.049moldm-³

(1biii)
No of moles of Fe²+ in the volume of B pipetted
n= cv/1000 =
0.151×25.0/1000 =
3.775/1000
= 0.003775moles of Fe²+

2a)
-Observation-
part of the C dissolves,colourless filtrate salt

-Inference-
C is a mixture of soluble salt

2bi)
-observation-
white precipitate formed

-Inference-
Cl is present

2bii)
-Observation-
precipitate dissolves

-Inference-
Cl confirmed

2biii)
-Observation-
colourless gas evolved with characteristic choking smell, turns litimus paper blue

-Inference-
Gas is NH3

2c)
-Observation-
Residue dissolves liberating a colourless gas which turns lime water milky

-Inference-
gas is CO2
CO^2-3 present

3i)
A white precipitate of barium sulphate will be formed by the instant reaction between barium chloride and sulphuric acid.
BaCl2 + H2SO4 = BaSO4 + 2HCl

3b)
Iron sulfide reacts with hydrochloric acid, releasing the malodorous (rotten egg smell) and very toxic gas,hydrogen sulphide. FeS + 2 HCl → FeCl2+ H2S

3c)
The iron dissolves, releasing hydrogen and making an iron chloride solution:
Fe + 2HCl → FeCl₂ + H₂

Make Sure You Subscribe If You Don’t Want To Be On Hot Sit
WE DON’T TALK MUCH

Become A Fan On Facebook