Answer:
Mole fraction of solute is 0.0462
Explanation:
To solve this we use the colligative property of lowering vapor pressure.
First of all, we search for vapor pressure of pure water at 25°C = 23.8 Torr
Now, we convert the Torr to mmHg. Ratio is 1:1, so 23.8 Torr is 23.8 mmHg.
Formula for lowering vapor pressure is:
ΔP = P° . Xm
Where ΔP = P' (Vapor pressure of solution) - P° (Vapor pressure of pure solvent)
Xm = mole fraction
24.9 mmHg - 23.8 mmHg = 23mmHg . Xm
Xm = (24.9 mmHg - 23.8 mmHg) / 23mmHg
Xm = 0.0462
Carbon(C):
number of moles= mass/molar mass(Mr)
=65.5/12
=5.5 moles
Hydrogen(H):
number of moles=mass/molar mass (Mr)
=5.5/1
=5.5 moles
Oxygen (O):
number of moles = mass/molar mass (Mr)
=29.0/16
=1.8 moles
EF= lowest number of moles over each of the elements
So,
C= 5.5/1.8 = 3
H= 5.5/1.8 = 3
O= 1.8/1.8 = 1
Therefore Emperical formula= C3H3O
Spectrophotometric cell or a cuvette is made of quartz for UV spectrophotometers. These cuvettes are used as sample holders for the spectrophotometric determination of the analytes. The material that makes up the cuvette and the condition of the cuvette is to be taken care of in order to avoid erroneous absorbance readings. The sample holder or the cuvette must be removed from the spectrophotometer in between two successive readings. This is to ensure that the light sensing detector of the instrument is not affected.
