1) A quantity of 8.228 g of an organic compound is dissolved in water to make 33
ID: 562702 • Letter: 1
Question
1) A quantity of 8.228 g of an organic compound is dissolved in water to make 330.0 mL of solution. The solution has an osmotic pressure of 1.43 atm at 27°C. The analysis of this compound shows that it contains 41.8 percent C, 4.7 percent H, 37.3 percent O, and 16.3 percent N. Calculate the molecular formula of the compound.
2)A 257mL sample of a sugar solution containing 1.79 g of the sugar has an osmotic pressure of
30.6 mmHg at 35.3°C. What is the molar mass of the sugar?
Please help me, I've been looking at examples for hoursssss
Explanation / Answer
osmotic pressure(P) = cRT
P = (w/M)*(1000/V)*RT
1.43 = (8.228/M)*(1000/330)*0.0821*300.15
M = MOLARMASS OF O.C = 429.6 g/mol
from the given data
C = 41.8/12 = 3.483
H = 4.7/1 = 4.7
O = 37.3/16 = 2.331
N = 16.3/14 = 1.164
simplest whole number ratio,
C = 3.483/1.164 = 3
H = 4.7/1.164 = 4
O = 2.331/1.164 = 2
N = 1.164/1.164 = 1
empirical formula = C3H4O2N
empirical formula MASS = 86
n = 429.6/86= 5
molecular formula = 5*(C3H4O2N) = C15H20O10N5
2)
osmotic pressure(P) = cRT
P = (w/M)*(1000/V)*RT
(30.6/760) = (1.79/M)*(1000/257)*0.0821*(35.3+273.15)
M = molarmass of O.C = 4380.66 g/mol
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