1) The boiling point of water H 2 O is 100.00 °C at 1 atmosphere. A nonvolatile,

Question

1) The boiling point of water H2O is 100.00°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in water is urea. If 14.23 grams of urea, CH4N2O (60.10 g/mol), are dissolved in 293.7 grams of water. The molality of the solution is  m. The boiling point of the solution is  °C.

2) The boiling point of water H2O is 100.0°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in water is glucose . How many grams of glucose, C6H12O6 (180.2 g/mol), must be dissolved in 249.0 grams of water to raise the boiling point by 0.450 °C ? in g glucose.

3) The freezing point of ethanol CH3CH2OH is -117.30°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in ethanol is testosterone . If 11.04 grams of testosterone, C19H28O2 (288.4 g/mol), are dissolved in 196.4 grams of ethanol ...The molality of the solution is  m. The freezing point of the solution is  °C.

4) The freezing point of benzene, C6H6, is 5.500 °C at 1 atmosphere. Kf(benzene) = 5.12 °C/m In a laboratory experiment, students synthesized a new compound and found that when 14.23 grams of the compound were dissolved in 295.8 grams of benzene, the solution began to freeze at 4.596 °C. The compound was also found to be nonvolatile and a non-electrolyte. What is the molecular weight they determined for this compound?  g/mol

5) The freezing point of benzene, C6H6, is 5.500 °C at 1 atmosphere. Kf(benzene) = 5.12 °C/m In a laboratory experiment, students synthesized a new compound and found that when 13.24 grams of the compound were dissolved in 222.7 grams of benzene, the solution began to freeze at 4.713 °C. The compound was also found to be nonvolatile and a non-electrolyte. What is the molecular weight they determined for this compound?  g/mol

6) The boiling point of ethanol, CH3CH2OH, is 78.500 °C at 1 atmosphere. Kb(ethanol) = 1.22 °C/m In a laboratory experiment, students synthesized a new compound and found that when 11.04 grams of the compound were dissolved in 230.9 grams of ethanol, the solution began to boil at 78.818 °C. The compound was also found to be nonvolatile and a non-electrolyte. What is the molecular weight they determined for this compound ?  g/mol

Explanation / Answer

1)

Lets calculate molality first

Molar mass of CH4N2O,

MM = 1*MM(C) + 4*MM(H) + 2*MM(N) + 1*MM(O)

= 1*12.01 + 4*1.008 + 2*14.01 + 1*16.0

= 60.06 g/mol

mass,m = 14.23 g

number of mol,

n = mass/molar mass

= 14.23/60.06

= 0.237 mol

mass of solvent ,m = 293.7 g = 0.2937 Kg

Molality,

m = number of mol / mass of solvent in Kg

= 0.237/0.2937

= 0.807 M

lets now calculate Tb

Tb = Kb*m

= 0.512*0.807

= 0.413 oC

This is increase in boiling point

freezing point of pure liquid = 100.0 oC

So, new boiling point = 100 + 0.413

= 100.413 oC

Answer: 100.4 oC

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