338
Colhgative Properties
29 A common way to check the purity of a compound is to take its melting point,
because any soluble impurity always lowers the melting point What is the
molal concentration of impurity in urethane if its melting point is 47 7°C
9
30 When 1 645 g of phosphorus is dissolved in 60 0 ml of CS 2 (density = 1 263
g/ml), the solution boils at 46 709°C, CS 2 alone boils at 46 300°C What is the
molecular formula of phosphorus
9
31 By analysis, a certain solid organic compound is found to be 40 0% C, 6 1%
H, and 53 3% O When a 0 650 g sample of this compound is dissolved in
27 80 g of diphenyl, the freezing point is lowered by 1 56°C Determine the
true formula of this compound
32 A certain solid organic compound is analyzed as 18 3% C 0 51% H, and
81 2% Br When 0 793 g of this compound is dissolved in 14 80 ml of
chloroform (density = 1 485 g/ml), whose boiling point is 60 30°C, the solution is found to boil at 60 63°C What is the true formula of this compound
9
33 How many quarts of ethylene glycol, C 2 H 6 O 2 (density =1115 g/ml), must be
added to 5 0 gal of water (density = 1 00 g/ml) to protect an automobile
radiator down to a temperature of -15 0°F
9 (Ethylene glycol is a permanent" antifreeze agent)
34 What is the vapor pressure at 25 0°C of an aqueous solution containing 100 g
glycerine, C 3 H 8 O 3 , in 150 g of water
9
35 What is the osmotic pressure of a solution in which 50 0 g of sucrose,
C 12 H 22 O n , is dissolved in 150 g of water at 21 0°C
9
36 If an aqueous glucose (C 6 H 12 O 6 ) solution has an osmotic pressure of 50 0 atm
at 35 0°C, what will be its vapor pressure at the same temperature
7
37 A solution containing 1 259 g of a certain protein fraction per 100 g of water is
found to have an osmotic pressure of 8 32 cm of Hater at 28 0°C Calculate the
mole weight of the protein fraction The density of water is 1 00 g/ml, that of
Hgis 13 6 g/ml
38 A 0 70% solution of a certain plant polysacchande (complex plant sugar) has
an osmotic pressure of 6 48 torr at 21 0°C Of how many simple sucrose sugar
units, C 12 H 2 2O n , must this polysacchande be composed
1
39 A 0 0200 molal aqueous solution of picric acid, HCt,H 2 O 7 N 3 , freezes at
—0 0656°C Picric acid ionizes to a certain extent in water, as
HC 6 H 2 0 7 N 3 -> H
+ + C 6 H 2 0 7 N 3 -
Calculate the percentage of icnization of picric acid at this temperature
40 A 0 200 molal NaNO 3 solution freezes at -0 665°C What is its apparent
percentage of lomzation
9
41 A 0 100 molal solution of HNO 2 in water is 6 50% ionized What will be the
freezing point of this solution
9
Colhgative Properties
29 A common way to check the purity of a compound is to take its melting point,
because any soluble impurity always lowers the melting point What is the
molal concentration of impurity in urethane if its melting point is 47 7°C
9
30 When 1 645 g of phosphorus is dissolved in 60 0 ml of CS 2 (density = 1 263
g/ml), the solution boils at 46 709°C, CS 2 alone boils at 46 300°C What is the
molecular formula of phosphorus
9
31 By analysis, a certain solid organic compound is found to be 40 0% C, 6 1%
H, and 53 3% O When a 0 650 g sample of this compound is dissolved in
27 80 g of diphenyl, the freezing point is lowered by 1 56°C Determine the
true formula of this compound
32 A certain solid organic compound is analyzed as 18 3% C 0 51% H, and
81 2% Br When 0 793 g of this compound is dissolved in 14 80 ml of
chloroform (density = 1 485 g/ml), whose boiling point is 60 30°C, the solution is found to boil at 60 63°C What is the true formula of this compound
9
33 How many quarts of ethylene glycol, C 2 H 6 O 2 (density =1115 g/ml), must be
added to 5 0 gal of water (density = 1 00 g/ml) to protect an automobile
radiator down to a temperature of -15 0°F
9 (Ethylene glycol is a permanent" antifreeze agent)
34 What is the vapor pressure at 25 0°C of an aqueous solution containing 100 g
glycerine, C 3 H 8 O 3 , in 150 g of water
9
35 What is the osmotic pressure of a solution in which 50 0 g of sucrose,
C 12 H 22 O n , is dissolved in 150 g of water at 21 0°C
9
36 If an aqueous glucose (C 6 H 12 O 6 ) solution has an osmotic pressure of 50 0 atm
at 35 0°C, what will be its vapor pressure at the same temperature
7
37 A solution containing 1 259 g of a certain protein fraction per 100 g of water is
found to have an osmotic pressure of 8 32 cm of Hater at 28 0°C Calculate the
mole weight of the protein fraction The density of water is 1 00 g/ml, that of
Hgis 13 6 g/ml
38 A 0 70% solution of a certain plant polysacchande (complex plant sugar) has
an osmotic pressure of 6 48 torr at 21 0°C Of how many simple sucrose sugar
units, C 12 H 2 2O n , must this polysacchande be composed
1
39 A 0 0200 molal aqueous solution of picric acid, HCt,H 2 O 7 N 3 , freezes at
—0 0656°C Picric acid ionizes to a certain extent in water, as
HC 6 H 2 0 7 N 3 -> H
+ + C 6 H 2 0 7 N 3 -
Calculate the percentage of icnization of picric acid at this temperature
40 A 0 200 molal NaNO 3 solution freezes at -0 665°C What is its apparent
percentage of lomzation
9
41 A 0 100 molal solution of HNO 2 in water is 6 50% ionized What will be the
freezing point of this solution
9