5.17 Demo 02 November 2011 19:56 Cloud formation
· Place a little water in the bottom of a 1½ litre plastic bottle
· Squeeze a few times
· Introduce a small amount of smoke
· Squeeze and release several times
· When you squeeze, the cloud disappears; when you release, the cloud reforms Explanation
· When the pressure increases the temperature increases and vica versa
· The smoke particles are nucleating sites on which the water can condense ANSWERS Collins) p1/T1 = p2/T2 => 3/293 = p2/(273+55) => p2 = 3.4 bar a) The pressure decreases, as temperature decreases.
b) As the temperature decreases, the average kinetic energy of the particles decreases, meaning that they move around with less speed, and with less energy. This means that they hit the walls of the rigid container with less force, and since the surface area of the container is still the same (rigid container), according to the p = F/A law, the pressure decreases with temperature. (pressure is prop. to temperature) 5.18 Gay-lussac's law 28 October 2011 11:11
· 5.18 use the relationship between the pressure and Kelvin temperature of a fixed mass of gas at constant volume: p1 / T1 = p2 / T2 p1 = Pressure at the beginning [kPa, bar or atm ] T1 = Absolute temperature at the beginning [K] p2 = Pressure at the end [kPa, bar or atm] T2 = Absolute temperature at the end [K] (Note: the units of temperature must be Kelvin, not oC! The units of pressure can be any, as long as the same at the beginning and the end) 5.18 Ideal graph and conclusion 09 November 2011 15:15
[cid:image001.png@01CCA464.D69055D0] 5.18 Question 07 November 2011 15:08 Collins, p.116 [cid:image002.jpg@01CCA464.D69055D0]
a. If we cool the gas in a rigid, sealed tin can, what happens to the pressure inside the can? (1 mark)
b. Explain your answer to part a. by using the Kinetic Theory (4 marks)
· Place a little water in the bottom of a 1½ litre plastic bottle
· Squeeze a few times
· Introduce a small amount of smoke
· Squeeze and release several times
· When you squeeze, the cloud disappears; when you release, the cloud reforms Explanation
· When the pressure increases the temperature increases and vica versa
· The smoke particles are nucleating sites on which the water can condense ANSWERS Collins) p1/T1 = p2/T2 => 3/293 = p2/(273+55) => p2 = 3.4 bar a) The pressure decreases, as temperature decreases.
b) As the temperature decreases, the average kinetic energy of the particles decreases, meaning that they move around with less speed, and with less energy. This means that they hit the walls of the rigid container with less force, and since the surface area of the container is still the same (rigid container), according to the p = F/A law, the pressure decreases with temperature. (pressure is prop. to temperature) 5.18 Gay-lussac's law 28 October 2011 11:11
· 5.18 use the relationship between the pressure and Kelvin temperature of a fixed mass of gas at constant volume: p1 / T1 = p2 / T2 p1 = Pressure at the beginning [kPa, bar or atm ] T1 = Absolute temperature at the beginning [K] p2 = Pressure at the end [kPa, bar or atm] T2 = Absolute temperature at the end [K] (Note: the units of temperature must be Kelvin, not oC! The units of pressure can be any, as long as the same at the beginning and the end) 5.18 Ideal graph and conclusion 09 November 2011 15:15
[cid:image001.png@01CCA464.D69055D0] 5.18 Question 07 November 2011 15:08 Collins, p.116 [cid:image002.jpg@01CCA464.D69055D0]
a. If we cool the gas in a rigid, sealed tin can, what happens to the pressure inside the can? (1 mark)
b. Explain your answer to part a. by using the Kinetic Theory (4 marks)
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