(a) At what temperature does water boil at an altitude of 1500 m (about 5000 ft) on a day when atmospheric pressure is $8.59\times 10^4{\text{ N/m}}^2$? (b) What about at an altitude of 3000 m (about 10,000 ft) when atmospheric pressure is $7.00\times 10^4{\text{ N/m}}^2$?

Video Transcript

This is College Physics Answers with Shaun Dychko. Boiling occurs when the vapor pressure of the liquid equals the pressure of the gas above it. So in this case we have the atmosphere and the pressure of the atmosphere is different in parts A and B because we are at different altitudes. So, at an altitude of 1,500 meters, the pressure is 8.59 times 10 to the four newtons per square meter. So we look up in table 13.5 to find out what temperature does the vapor pressure of water equal that much. So 8.59 times 10 to the four corresponds to 95 degrees Celsius and so that's going to be when the water boils. And then at 3,000 meters, the atmospheric pressure is seven times 10 to the four newtons per square meter and that corresponds to about 90 degrees Celsius. So boiling will occur at 90 degrees Celsius at 3,000 meters altitude.