Question

This graph shows how the vapor pressure of three liquids varies with temperature: vapor pressure, torr benzene - methanol - isopropyl acetate temperature, °C Use the graph to answer the following questions: most volatile: choose one - Which liquid is the most volatile? Which is the least volatile? least volatile: choose one benzene: I°C What is the normal boiling point of each liquid? he within 10 of the exact methanol:

Answer 1

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RESULTS:

1. Most volatile: Methanol.
2. Least volatile: isopropyl acetate.
3. Boiling point of Methanol: 65^oC
4. Boiling point of Benzene: 80^oC
5. Boiling point of isopropyl acetate: 88^oC
6. Amount of liquid will be the same.

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EXPLANATIONS:

PART 1:

We know that, Volatility is the measure of tendency of a liquid to vaporize.

A liquid having higher vapor pressure at a given temperature will have higher volatility.

From the given graph, we can see that the slope of the graph of methanol has a higher slope. Hence at a given temperature methanol will have higher vapor pressure and  isopropyl acetate will have least vapor pressure

Most volatile: Methanol.

Least volatile: isopropyl acetate.

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PART 2:

Boiling occurs when vapor pressure of the liquid becomes equal to atmospheric pressure.

We know that, atmospheric pressure is 1 atm= 760 torr.

Hence the temperature corresponding to 760 torr of each molecule will give their boiling point.

900- 800- vapor pressure, torr benzene - methanol isopropyl acetate 65 70 890 temperature,

From graph:

Boiling point of Methanol: 65^oC

Boiling point of Benzene: 80^oC

Boiling point of isopropyl acetate: 88^oC

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PART 3:

From graph, For methanol, at 57^oC, vapor pressure is nearly 500 torr.

900- vapor pressure, torr - benzene -methanol - isopropyl acetate temperature, °C

But the pressure inside the tank is 550 torr, hence the methanol will not boil because the pressure is greater than vapor pressure.

Hence, after 10 minutes, the amount of liquid will be the same.

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