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The Science of Gases

Student Assignment: Vapour Pressure of Water

The coffee in these cups will resist boiling up to 134°C.

Figure 1

Figure 2

1. From the graph shown in Figure 1 determine the temperature at which the vapour pressure of water is exactly one half standard atmospheric pressure.

2. From the graph shown in Figure 1 determine the atmospheric pressure at which water boils at 90°C.

3. Mountaineers observe that at their base camp the water used to make tea boils at exactly 85°C. Using information from both Figure 1 and then Figure 2 determine the altitude of their base camp.

4. Suppose astronauts worked in a pure oxygen environment where only the partial pressure of oxygen was present at exactly 20 kPa. What would be the maximum temperature at which they could heat water for making hot beverages without causing the water to boil?

5. Scientists working in the Aquarius underwater habitat are at a pressure of about 300 kPa inside the habitat. Predict the effect that pressure would have on the boiling point of water and explain your reasoning.

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