Question

Question 3 A rigid tank, of 0.5 m volume, contains an ideal-gas mixture at 300 K. The mixture is made up of 2.4 kg of gas A and 1.4 kg of gas B, the molecular weights of which are MA = 32.0 kg/kmole and M 28.0 kg/kmole, respectively. i. Determine the mass fraction of A and B. (3 marks] ii. Determine the mole fraction of A and B. [5 marks] iii. Determine the molecular weight of the mixture. [2 marks] iv. Determine the total pressure Post as well as the partial pressures PA and Ps. The universal gas constant R has the value of 8.31 kJ/kmole K. [3 marks) A cylinder fitted with a movable frictionless piston contains a mixture of dry air and water vapor. The piston is arranged in such a way that the total) pressure inside the cylinder remains constant at 100 kPa. Initially, the temperature of the mixture is 40°C, its dew.point temperature being 25°C. i. Determine the initial relative humidity, 41, of the mixture. [3 marks) ii. Determine the initial humidity ratio, wy, of the mixture. [3 marks) Now, the mixture inside the cylinder is cooled to the final temperature Tin order to partially condense the vapor in the mixture and to reduce its vapor content by 50% on a mass basis. iii. What is the humidity ratio, wz, of the remaining mixture? [2 marks] iv. What is the final temperature T2? [4 marks] Continued...

Answer 1

As per HOMEWORKLIB POLICY, first four sub-questions are answered as the student has not requested for particular questions.

V = 0.5 m² T= 300k MA=2.4 kg MB2 1.4 kg , MA= 32 kg/kmole MB = 28 kg/kmole Pi) Total mais of gas mixture m= mAtmB = 2.4+1.4 m = 3,8 kg mas fraction me: MEA = MA= 21% = 0.632 mfB = med = 14 = 0,368 SIR 1) Mole fraction nf Number of moles of gas A =nA= ma 2 .4 MA 32 - 175x103 knoke NA = 75 moles Similarly, 1. nB = MB = somoles 28 Total number of moles of gas n=nA +nB. = 75+ 50 =125 moles n #Aan het = 0.6

mamAtm B nm = NAMA + NOMB M= A MA + B MB - NAT MAT MAB MB - 0.6 x 32 + 0.4 x 28 м = 30 ч |Emote iv) Ideal gas law PV = nRT , R = 8.31 kJ / Knolek p = 125 X 8.31 x 300 0.5 P= 623.25 kPa. Similarles, PAV=MART many, PAU-HART , PAY partial preesure A PA = 75X81314x300 015 = 374.13 kPa OB 50x8.314x300 - 249.42 kPa 05