This Demonstration models the behavior of a sealed, 1-L autoclave that initially contains mostly water plus a small volume of air, all at 25°C. The initial volume of water is changed with a slider, and the temperature resets to 25°C when the initial water volume is changed. As the temperature increases by moving the slider, liquid water expands and its saturation pressure increases. At the same time, the gas-phase volume decreases, so gas-phase O₂ and N₂ partial pressures increase (ideal gas law). The amounts of O₂ and N₂ dissolved in the water increase with pressure, but decrease with temperature. The amounts dissolved are shown in the bar chart (green = gas phase, purple = dissolved). Even at moderate temperatures, the pressures inside the sealed container can be quite high.