Colligative Properties

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CHEMISTRY

-COLLIGATIVE PROPERTIES -

C O L L I G A T I V E   P R O P E R T I E S[pic 1]

                 Q U E S T I O N S

Q30. Calculate the vapor pressure of a solution of 90 g glucose in 1 L of water at .[pic 2][pic 3]

Given:

        90g [pic 4]

        30 degrees Celsius

        1L

Solution:        [pic 5]

[pic 6]

[pic 8][pic 7]

[pic 9]

   180 g/mol

[pic 10]

L[pic 11]

M= 0.5 M

Q31. What mass of naphthalene if dissolved in 257 g of benzene if the freezing point of the solution is 4.8C? (Use data in Table 2.5)[pic 12]

Given:

        257 g (benzene)

        4.8 degrees Celsius

        5.5 [pic 15]

        5.1 [pic 16]

Solution:

[pic 17]

Q32. What is the van’t Hoff constant ifor the following substances?

1. [pic 18]

CaCl₂: CaCl₂ → Ca²⁺ + 2Cl⁻, so i = 3

1. KI

KI: , so i = 2[pic 19]

1. [pic 20]

AlI: , so i = 4[pic 21]

1. [pic 22]

[pic 23]

Q33. In very cold countries, antifreeze is added to the water in the radiator. Explain how this works.

        "Antifreeze" is a chemical, primarily consisting of ethylene glycol, which when mixed with water serves to lower the freezing point and raise the boiling point of the mixture. Traditionally, the combination of antifreeze and water is known as "coolant". As opposed to air-cooled vehicles which rely on fan-driven air blowing over engine components, water-cooled engines use a radiator, water pump, thermostat, heater core, hoses, and passageways within the engine. Within this system, the coolant travels in a circular path driven by the water pump, through the engine where it removes heat generated by combustion, through the vehicle's heater core (supplies heat to the vehicle's interior), and through the radiator where its heat is shed to the outside air, to begin the cycle again.