a.) Two groups of students prepared the compound acetamide. Group A isolated is

Question

a.) Two groups of students prepared the compound acetamide. Group A isolated is a solid with a melting point of 80.5 degrees C. Group B obtained a compound with a melting point of 74-77 degrees C. When the students consulted the chemistry manual, acetamide was found to have a melting point of 82 degrees C. Which group prepared a more pure compound and why?

b.) The melting point of a solid may be defined as the temperature when both solid and liquid phases coexist. How may you define the boiling point of a substance?

c.) The boiling point of liquid is determined by heating it slowly and recording the temperature when the liquid vaporizes. Suppose a student doing the experiment heats the liquid up very rapidly. Is he likely to get the correct boiling point?

d.) The boiling point of a liquid on the pressure of its vapor over the liquid. Therefore the boiling point of water at the top of the Himalayan Mountain is lass than 100 degrees C. What is the melting point of ice on top of the Himalayan mountain?

Explanation / Answer

a) Group A prepared a more pure compound because there is a smaller deviation from original melting point of pure compound acetamide.

b) boiling point of liquid is the temperature at which its vapor pressure becomes equal to the external pressure.

c) No the student will not get the correct boiling point. This is because by the time he will note the boiling point the temperature of the system would have over shot the actual boiling point.

d) melting point of ice increases with decreasing external pressure. As hill region have lower atmospheric pressure therefore the melting point of ice on himalyas will be lower than 0 degree centigrade.

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