Topic overview

Start with the big picture

Pressure is expressed in pascals and commonly encountered in laboratory units such as atmospheres, bars, millimeters of mercury, and torr. Converting between units and distinguishing gauge pressure from absolute pressure provide a practical starting point. The lesson then connects pressure with volume, temperature, and amount of gas through the ideal gas law and named gas laws, and explains how Dalton’s law relates total pressure to component gases. Further topics include vapor pressure and its temperature dependence, pressure measurement with manometers and barometers, and hydrostatic pressure in fluids. The chapter also introduces pressure changes with altitude, critical pressure, real-gas deviations, and pressure’s role in molecular collisions.