Question

Problem 5 A rigid tank of 2m contains pure nitrogen gas at 800kPa and 400K. A mass of 1.8kg is removed from the tank. The final temperature is 375K. What is the final pressure? Problem 6 A glass is cleaned in hot water and reaches a temperature of 50°C. The glass is placed on a table bottom up. The room temperature air trapped in the glass heats up to 45°C, and some of the air escapes, so that the resulting pressure in the glass is 2kPa higher than the ambient pressure of 100kPa. The glass and air is let to cool to 20°C. What is the pressure inside the glass?

Answer 1

Ans. 5 Gas Constant for Nitrogen Gas (N2). R = R Molecular Mass of Nitrogen Gas R = 8.314 kileg) kar 28.014 X10-3 R=296.78 TL Rigid tank is given means volume remains constant v= 2m3 i.e. Vi =Vg = V. P = 800 kPa = 800 x 10² Pa T = Hook using equation & P, V, = MRT 800x103 x2= mx 296.78 x You m=13.48 kg of nitrogen gas. When 108 kg of mass cof nitrogen gas is removed from tank. mass of nitrogen gas left in tank m'- 13:48 - 1.8 m= 11.68 kg To = 375k using equation - P V₂ = MR Ta

P = MRT2 - 11.68 × 296.78 × 375 P = 649948. 2 Pa P = 649.948 Pa P= 649.95 Pa = final pressure.