Question

Molecular Mass of a Volatile Liquid 1. The atmospheric pressure of a hot summer day in NYC is 29.94 inHg. Calculate this value in mmile and am 2. The atmospheric pressure of a cold winter day in NYC is 25.94 inHg. Calculate this value in Pa. 3. We set up an experiment utilizing the Dumas method to calculate the molar mass of an unknown chemical. A 4.00 mL pure liquid sample of this chemical is vaporized in an Erlenmeyer flask with a volume of 155 mL, when the barometric pressure is 1.01 atm. The empty flask weighs 25.2436 g. After the excess gas escapes, the temperature is measured as 97.0°C. The flask and contents are subsequently cooled and the vapor condenses to a liquid. The weight of the flask and contents is found to be 25.7843 g. Calculate the molar mass of the unknown liquid.

Answer 1

1.(a)

1 inHg = 25.4 mmHg

So,

29.94 inHg = 29.94 x 25.4 mmHg

= 760.476 mmHg

Hence, 29.94 inHg = 760.476 mmHg

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1.(b)

1 inHg = 0.0334211 atm

So,

29.94 inHg = 29.94 x 0.0334211 atm

= 1.00063 atm

Hence, 29.94 inHg = 1.00063 atm

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2.

1 inHg = 3386.39 Pa

So,

25.94 inHg = 25.94 x 3386.39 Pa

= 87842.9 Pa

Hence, 25.94 inHg = 87842.9 Pa

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