Answer:
Molar mass of unknown solute is 679 g/mol
Explanation:
Let us assume that the solute is a non-electrolyte.
For a solution with non-electrolyte solute remains dissolved in it -
Depression in freezing point of solution, ![\Delta T_{f}=K_{f}.m](https://tex.z-dn.net/?f=%5CDelta%20T_%7Bf%7D%3DK_%7Bf%7D.m)
where, m is molality of solute in solution and
is cryogenoscopic constant of solvent.
Here ![\Delta T_{f}=(-22.9^{0}\textrm{C})-(-28.7^{0}\textrm{C})=5.8^{0}\textrm{C}](https://tex.z-dn.net/?f=%5CDelta%20T_%7Bf%7D%3D%28-22.9%5E%7B0%7D%5Ctextrm%7BC%7D%29-%28-28.7%5E%7B0%7D%5Ctextrm%7BC%7D%29%3D5.8%5E%7B0%7D%5Ctextrm%7BC%7D)
If molar mass of unknown solute is M g/mol then-
![m=\frac{\frac{2.2}{M}}{0.0167}mol/kg](https://tex.z-dn.net/?f=m%3D%5Cfrac%7B%5Cfrac%7B2.2%7D%7BM%7D%7D%7B0.0167%7Dmol%2Fkg)
So, ![5.8^{0}\textrm{C}=29.9^{0}\textrm{C}/(mol/kg)\times \frac{\frac{2.2g}{M}}{0.0167}mol/kg](https://tex.z-dn.net/?f=5.8%5E%7B0%7D%5Ctextrm%7BC%7D%3D29.9%5E%7B0%7D%5Ctextrm%7BC%7D%2F%28mol%2Fkg%29%5Ctimes%20%5Cfrac%7B%5Cfrac%7B2.2g%7D%7BM%7D%7D%7B0.0167%7Dmol%2Fkg)
so, M = 679 g/mol
CH2OHCH2OH is a
general example of a polyhydroxyl alcohol. A polyhydroxyl alchol is one in which
there are two hydroxyl groups present in the substance. The –OH group attached
to both the carbon atoms.
Answer:
Mole fraction O₂= 0.43
Explanation:
Mole fraction is the moles of gas/ total moles.
Let's determine the moles of each:
Moles O₂ → 15.1 g / 16 g/mol = 0.94
Moles N₂ → 8.19 g / 14 g/mol = 0.013
Moles H₂ → 2.46 / 2 g/mol = 1.23
Total moles = 2.183
Mole fraction O₂= 0.94 / 2.183 → 0.43