Given:
Empirical formula of a non-electrolyte =
CH2O Mass of compound taken = 6 g
Concentration of glucose solution = 0.05 M
(Osmotic‌pressure)compound =
(Osmotic‌pressure)glucose We have to find !tie molecular formula of the compound
Now, the empirical formu!a mass of
CH2O is:
= 12 + 2 × 1 + 16 = 30
Let molar mass of the compound be 'M'.
Let osmotic pressure of the compound and glucose be
Ï€1 and
Ï€2 respectively and as given:
(Osmotic‌pressure)compound =
(Osmotic‌pressure)glucose or,
Ï€1 =
Ï€2 Thus,
C1RT =
C2RT or,
C1 =
C2 ... (i)
where,
C1 = Concentration of solution of compound
C2 = Concentration of glucose solution
R = Gas constant
T = Temperature
Now, molarity is given by:
Molarity =
| Number‌of‌moles |
| Volume‌of‌solution(in‌L) |
Number of moles is given by :
Mole =
Thus,
C1 =
From equation (i) , we get
= 0.05
M =
= 120
Now,
n =
| Molecular‌mass |
| Empirical‌formula‌mass |
... (ii)
where, n = Simple whole number
Substituting the values in equation (ii). we get
n =
= 4
Therefore, molecular formula of the compound =
(CH2O)n =
(CH2O)4 =
C4H8O4 Hence, option 'D' is correct.