A laboratory pressure chamber allows the external pressure around a sealed glass bulb to be varied while the gas inside the bulb remains at constant temperature and constant mass. Initially, with the chamber open to the atmosphere at sea level (1.013×105Pa), the gauge fitted to the bulb shows 150kPa.
(i) Calculate the absolute pressure of the gas inside the bulb under this initial condition.
(ii) The chamber pressure is now increased to 1.20atm while the bulb remains sealed. Determine the new gauge pressure reading for the gas in the bulb.
(iii) The chamber pressure is next reduced to 0.60atm. Find the gauge pressure under this condition and comment on whether the gauge will register a positive or negative value.
(iv) Explain how the results in parts (ii) and (iii) illustrate the difference between gauge pressure and absolute pressure.