Please answer all. If the mole fraction of a solution of octane (C_8H_18) in ben
ID: 526041 • Letter: P
Question
Please answer all.
If the mole fraction of a solution of octane (C_8H_18) in benzene (C_6H_6) is 0.24, what is the molality of octane in the solution? Atomic masses are: C 12.01, H 1.01 What is the experimentally determined concentration of particles for an 1.01 molal solution of an ionic substance in water if the boiling point of the solution is 100.1 delta C? The boiling point elevation constant K_bo, for water is 0.5121 K (kg solvent) (mol solute)^-1. Present your answer as a numerical value only, to 3 significant figures in the form x.xxEx. A solution is prepared up by dissolving 26.5 g of ethanol, CH_3CH_2OH, in 1433 g of water. What is the molality of ethanol in the solution? Atomic masses are: C 12.01, H 1.01, O 16.00Explanation / Answer
1..mole fraction =. Solute(Xn)+solvent (XN) =1 so if octane as a solute have 0.24 (Xn)than solventAs benzene will have 0.76(XN) and total have =1.so now
. If solut in 240 gm than solvent should be 760 gm.and toal hae =1000 gm
Now molality =. Weight *1000/molecular weight*weight of solvent(gm)
. = 240*1000/114.23*760
. =2.764 molekg
molecular wight octane =114.23 gmmole
2... Tb = Tb - T
=100.1-100
=0.1 degree Celsius
Now. Tb = Kbcm
0.1=0.5121*x
=0.1/0.5121
0.1952
vanthaff factor for ionic substance will =dissociated ions like Nacl have 2
The boiling point of pure water is 100°C, but that boiling point can be elevated by the adding of a solute such as a salt. A solution typically has a measurably higher boiling point than the pure solvent.
A treatment of boiling point elevation is given by Ebbing. The boiling point elevation Tb is a colligative property of the solution, and for dilute solutions is found to be proportional to the molal concentration cm of the solution:
Tb = Kbcm
Where Kb is called the boiling-point-elevation constant.
Solutions may be produced for the purpose of raising the boiling point and lowering the freezing point, as in the use of ethylene glycol in automobile cooling systems. The ethylene glycol (antifreeze) protects against freezing by lowering the freezing point and permits a higher operating temperature by raising the boiling point.
3... molality =. Weight *1000/molecular weight*weight of solvent(gm)
= 26.5*1000/46.068*143.3
= 4.014 mole/kg
Molecular weight of ethanol=46.068 gm/mole