King Saud University Chemical Engineering Department ChE 205: Chemical Engineeri
ID: 475919 • Letter: K
Question
King Saud University Chemical Engineering Department ChE 205: Chemical Engineering Thermodynamics I Time allowed: min Given by Dr. M. K. Hadikali Second Mid-Herm is to be heated at constant volumes woliLitstemperature An ideal gas 120C and what is the heat transfermed daring process 360C What is its final What are the main components of a heat engine? A central power plant, rated at goppgo kw, generates steam at 300"C and discards heat so a river at 25 C. What is the maximam possible thermal efficiency? lrthe thermal efficiency of the plant is 75% of the maximum possible value, how much heat is discarded to the river at nated power? Estimate of ethylene (cally contained ina02s m' eylinder a socat 30 bar. the mass A natural gas fuel contains 85 mol-% methane. 10 mol ethane and s moln narrogen. What is the standard heat ofcombustion (J mol" ofthis fuel at 25 c with water gas product? Hints 0.087. For ethylene, M. 28 g/mol, T- 282.3 Pe 5040 bar, w 0.172 0.422 0.139 0.083 R "8.314 J moln K 83.14 bar cm mol KExplanation / Answer
Encircled Q1 answered
Answer:
Given data,
P = 30 bar = 30 x 105 N/m2 = 3 x 106 N/m2.
V = 0.25 m3.
R = 8.314 J/K.mole
T = 50 oC = 50 + 273 = 323 K
using these values let's find out numbber of moles of ethylen gas i.e. n =?
Assuming Ideal behaviour of ethylene gas we have Ideal gas equation as,
PV = nRT
n = PV / RT
n = (3x106 x 0.25) / (8.314 x 323)
n = 279.3
Mass of ethylene = n x Molecular wt = 279.3 x 28 = 7820 g
Mass of ethylene is 7820 g (approximately)
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