A portable espresso maker uses a miniature high-pressure nitrogen gas capsule to force hot water through coffee grounds.
The volume of the high-pressure gas capsule is 8.0 cm38.0\text{ cm}^38.0 cm3.
The initial pressure of the nitrogen gas inside the capsule is 15,000 kPa15,000\text{ kPa}15,000 kPa.
When the seal of the capsule is pierced, the gas expands into the headspace chamber above the water.
The gas expands to a total volume of 250 cm3250\text{ cm}^3250 cm3.
Calculate the new pressure of the gas, assuming the temperature remains constant during this initial expansion.
As the gas expands into the headspace, its temperature decreases. Using ideas about molecules, explain how this temperature decrease affects the pressure of the gas.
Some of the nitrogen gas molecules dissolve into the hot water. Suggest how this affects the pressure of the gas in the headspace and explain your answer.
When the brew valve is opened, the pressure of the gas forces the water through the coffee puck and out of the nozzle into a cup. The pressure outside the espresso maker is lower than inside. Suggest what happens to the dissolved nitrogen gas as the liquid exits the nozzle.
