A technician checks a small steel cylinder used to supply carbon dioxide to a greenhouse. Fig. 1 is a simplified diagram of the cylinder connected to a pres...
Question 1 Report
A technician checks a small steel cylinder used to supply carbon dioxide to a greenhouse. Fig. 1 is a simplified diagram of the cylinder connected to a pressure gauge. The cylinder contains a fixed mass of carbon dioxide gas. It is placed in a water bath and allowed to reach the temperature shown before the pressure is read. The technician must not heat the cylinder above its safe operating temperature. Carbon dioxide is a compound containing carbon and oxygen, but the same kinetic theory ideas apply to nitrogen or ammonia gas.
(a) Name the quantity shown by the gauge. [1]
(b) Describe how the gauge reading changes as the water bath temperature increases. [2]
(c) Explain this change using kinetic energy and collisions with the cylinder wall. [3]
(d) Use kinetic theory to explain why the gas pressure would fall if a valve were opened and some carbon dioxide escaped at constant temperature. [2]
Answer Details
(a) The gauge measures pressure [1].
(b) Pressure increases as water-bath temperature increases [1], because the mass and volume of gas are fixed [1].
(c) Gas particles gain kinetic energy [1] and move faster [1]. They make more frequent and/or more forceful collisions with the cylinder walls, increasing pressure [1].
(d) If gas escapes, fewer particles remain in the cylinder [1]. They collide with the walls less often, so the pressure falls [1]. Temperature is constant, so the decrease is due to the lower number of particles.
Download The App On Google Playstore
Everything you need to excel in your exams
