Need help me in chemistry!!? please????

Posted on 2015-09-03 06:10:00 in Chemistry by JANINA

1. A substance has a heat of vaporization of 16.69 kJ/mole. At 254.3 K it has a vapor pressure of 92.44 mm Hg. Calculate its vapor pressure at 275.7 K.

2. At 50.14 K a substance has a vapor pressure of 258.9 torr. Calculate its heat of vaporization in kJ/mol it if has a vapor pressure of 161.2 torr at 277.5 K.

3. The vapor pressure of water at 35 oC is 42.175 mm Hg. The vapor pressure of ethyl alcohol (C2H5OH) at 35 ?C is 100.5 mm Hg. What is the vapor pressure of a solution prepared by dissolving 250 g of C2H5OH in 375 g of H2O?

4. What will be the freezing point and boiling point of an aqueous solution containing 55.0 g of glycerol, C3H5(OH)3, and 250 g of water? Kb(H2O) = 0.51 oC/m and Kf = 1.86o C/m.

5. A solution is prepared from 25.0 g of benzene, C6H6, and 2.50 g of an unknown compound. The freezing point of this solution is 4.3oC. The normal freezing point of benzene is 5.5 oC and the freezing point depression constant for benzene is 5.12 oC/m . Determine the molar mass of the compound.

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