Boiling Point of Water at Different Altitudes

Water boils at different temperatures depending on the air pressure. Air pressure is a measure of the weight per unit area of the air above a given location. At sea level the weight of air above a 1 inch square is 14.7 pounds. In the metric system, the weight of air above a 1 meter square is 1.01325 x 10⁵ Newtons. At higher altitudes, there is less air above any given point so the air pressure is lower. Thus different altitudes above sea level will have different boiling temperatures.

The table below lists the boiling temperature in degrees Fahrenheit versus altitude in increments of 1000 feet. Thus at sea level, the boiling temperature of water is 212 degrees Fahrenheit and at 10,600 feet above sea level, the boiling temperature of water is 193 degrees Fahrenheit.

Boiling temperatures of water

Using a statistical package or a graphing calculator, make a scatterplot of this data set with the degrees in Fahrenheit as the independent variable and the altitude in increments of 1000 feet as the dependent variable.

Fit a line and a quadratic to this data set and discuss which equation best fits the data set. For a reminder of how to choose which equation fits best, go here.

Using the quadratic equation, find the predicted boiling point of water at the top of Pikes Peak which has an altitude of 14,110 feet.

Find the predicted boiling point at the town in which you live.

If the boiling point is 200 degrees Fahrenheit, what is the altitude?