Burrette Reading(cm^3)|Rough|1st |2nd |3rd |
Final reading: |26.70|23.40|24.50|43.10|
Initial reading: |1.00 |1.00 |1.00 |20.00|
Volume of acid used: |25.70|22.40|24.50|22.80|
Average titre value= 1st+2nd+3rd/3=22.41+24.50+22.80/3 = 69.71/2= 23.23 cm3......
(Bi). Concentration of A in moldm-3.
Civi=Covo
2.0 * 13.2 = C0 * 250.
Co = 2.0 * 13.2/250 = 0.106moldm3.
(Bii) Cava/cbvb = a/b.
Ca=0.106moldm3.
Cb=?
Va= 23.23
Vb=25cm3
a=2,b=1
Cb = CaVab/vb.a
=0.106*23.3*1/ 25*2
=0.049moldm3.
(Biii)14.3g of Na2 Co3.nH2O in 1000cm3.
Mass of anhydious salt in 95.40cm3.
95.40cm3 * (23*2+12+16*3).
=95.40*106.
=10.12g.
Therefore, d value of n= mass of hydrated/ mass of an hydrous = molar mass of an hydrous/molar mass of water.
14.3/10.12 = 106/18n
(iii)7.15g in 500cm3
14.3 of Na2Co3.nH2O
n=106*10.12/18*14.3
n=(106*10.12)
(18*14.3) = n=4.2
percentage of water of crystallisation.
%=mass of water/mass of hydrated * 100/1
=14.3-10.12/14.3 * 100/1
=33.5 ans.
2. SALT ANALYSIS
(a.) TEST: Sample C+heat
OBSERVATION: Effervescence occur, white fumes is observed. Fumes is irritating.
INFERENCE: Cl- is present
Cl2(g) is liberated.
(bi)TEST: Sample C+10cm3 of H20+Stir
OBSERVATION: Dissolves to give a colourless solution.
INFERENCE: C is a soluble salt.
(bii)TEST: solution C+litmus paper.
OBSERVATION: turns blue litmus paper hcl.
INFERENCE: solution C is acidic..
(Ci)TEST: solution C+HNO3 in drops.
OBSERVATION: no visible reaction.
INFERENCE: CL- is suspected.
*TEST:solution C+HNO3+1CM3 of Ag N03.
OBSERVATION: forms white precipitate.
INFERENCE: CL- is presnt.
*TEST:solution+HNO3+AgNO3+NH3 in excess:
OBSERVATION: white ppt is insoluble.
INFERENCE: CL- is confirmed.
(cii)TEST:solution C+NaOH in drops.
OBSERVATION: forms white galatinous ppt.
INFERENCE: Ca2+, 2n2+, pb2+, Al3+ is suspected.
*TEST:solution:C+NaoH in excess.
OBSERVATION: white ppt dissolves in excess.
2n2+,pb2+,Al3+ is suspected.
*TEST:solution C+NaoH+warming.
OBSERVATION...white gelatinous ppt reappears on warming...
INFERENCE: 2n2+ is present.
(ciii)TEST:solution C+Ba Cl2.
OBSERVATION: forms white gelatinous ppt.
INFERENCE. CO2^-3, SO2^-3, SO2^-4 is suspected.
*TEST: solution C+BaCL2+HCL in excess.
OBSERVATION: white ppt is insoluble.
INFERENCE: SO2^-4 is confirmed.
(Civ)TEST: solution C+NH3 in drops.
OBSERVATION.
White gelatinous ppt.
INFERENCE: 2n2+, Pb2+, AL2+ is suspected.
*TEST:solution C+NH3 in excess.
OBSERVATION: white gelatinous ppt dessolves.
INFERENCE: 2n2+ is confirmed.
