1) When 20 cm3 of a gaseous hydrocarbon were sparked with 150cm3
of oxygen and the residual gases cooled to rtp, a contraction of
60cm3 occured. A further contraction of 80cm3 took place when the
residual gases were subjected to aq NaOH. All the vols were
measured at 20 degrees.
This is my workings.
Initial volume: CxHy =
20
X+y/4 O2 = 150
FInal volume: excess
volume of O2 = Z Volume
of Co2 = 110-Z
After Naoh: Co2
removed, 110-Z = 80
Z=30
Thus, X+ y/4
=150-30(excess)
X = 80 (volume of Co2)
X:Y
=80:160
=1:2
Thus CxHy = CH2
2) Write a balenced equation between KNO2 and KMnO4 given tat
half eqn for oxidation of NO2- to NO3- is
H20 + NO2- -> NO3-
+ 2H+ + 2e-
Basically i dont know whats the
skeleton eqn. Or i dont really know how to determine the products
of KNO2 and KMnO4
3)25cm3 of solution containing sodium hydroxide and sodium
carbonate required 22 cm3 of hcl acid with phenolphthalein as
indicator and a further 6.40cm3 of it with methy orange as
indicator.
Just wanna know is the vol of HCL
required to react with NAOH =
22 -6.4 ?
Also when asked to calculate the conc of sodium
carbonate, do i use 12.80cm3 as volume?
