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{
"metadata": {
"name": "",
"signature": "sha256:f533717d02de2958b8edaf7535383653f756ad9b4060abf4f556950fcb3e683e"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 3: Importance of State Functions: Internal Energy and Enthalpy"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example Problem 3.2, Page Number 45"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log\n",
"#Variable Declaration\n",
"betaOH = 11.2e-4 #Thermal exapnasion coefficient of ethanol, \u00b0C\n",
"betagl = 2.00e-5 #Thermal exapnasion coefficient of glass, \u00b0C\n",
"kOH = 11.0e-5 #Isothermal compressibility of ethanol, /bar\n",
"dT = 10.0 #Increase in Temperature, \u00b0C\n",
"\n",
"#Calcualtions\n",
"vfbyvi = (1+ betagl*dT)\n",
"dP = betaOH*dT/kOH-(1./kOH)*log(vfbyvi)\n",
"\n",
"#Results\n",
"print 'Pressure increase in capillary %4.1f bar'%dP"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Pressure increase in capillary 100.0 bar\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example Problem 3.4, Page Number 49"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"cpsubysy = 1000 #Specific heat ration of surrounding and system\n",
"Tpreci = 0.006 #Precision in Temperature measurement, \u00b0C\n",
"\n",
"#Calcualtions\n",
"dtgas = -cpsubysy*(-Tpreci)\n",
"\n",
"#Results\n",
"print 'Minimum detectable temperature change of gas +-%4.1f \u00b0C'%dtgas"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Minimum detectable temperature change of gas +- 6.0 \u00b0C\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example Problem 3.6, Page Number 50"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from sympy import symbols, integrate\n",
"\n",
"#Variable Declaration\n",
"n = 1.0 #number of mole of N2, mol \n",
"Ti = 200.0 #Intial Temperature, K\n",
"Pi = 5.00 #Initial pressure, bar\n",
"Tf = 400.0 #Intial Temperature, K\n",
"Pf = 20.0 #Initial pressure, bar\n",
"a = 0.137 #van der Waals constant a, Pa.m3/(mol2)\n",
"b = 3.87e-5 #van der Waals constant b, m3/(mol)\n",
"A, B, C, D = 22.5, -1.187e-2,2.3968e-5, -1.0176e-8\n",
" #Constants in Cvm equation J, K and mol\n",
"vi = 3.28e-3 #initial volume, m3/mol\n",
"vf = 7.88e-3 #Final volume, m3/mol\n",
"\n",
"#Calculations\n",
"T = symbols('T')\n",
"dUT = n**2*a*(1./vi-1./vf)\n",
"dUV = integrate( A + B*T + C*T**2 + D*T**3, (T,Ti,Tf))\n",
"\n",
"#Results\n",
"print 'dUT = %4.1f J: This is wrongly reported in book'%dUT\n",
"print 'dUV = %4.1f J'%dUV"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"dUT = 24.4 J: This is wrongly reported in book\n",
"dUV = 4174.1 J\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example Problem 3.7, Page Number 53"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from sympy import symbols, integrate\n",
"\n",
"#Variable Declaration\n",
"m = 143.0 #Mass of graphite, g \n",
"Ti = 300.0 #Intial Temperature, K\n",
"Tf = 600.0 #Intial Temperature, K\n",
"A, B, C, D, E = -12.19,0.1126,-1.947e-4,1.919e-7,-7.8e-11\n",
" #Constants in Cvm equation J, K and mol\n",
"M = 12.01\n",
"\n",
"#Calculations\n",
"\n",
"T = symbols('T')\n",
"dH = (m/M)*integrate( A + B*T + C*T**2 + D*T**3 + E*T**4, (T,Ti,Tf))\n",
"expr = A + B*T + C*T**2 + D*T**3 + E*T**4\n",
"cpm = expr.subs(T,300.)\n",
"qp = (m/M)*cpm*(Tf-Ti)\n",
"err = abs(dH-qp)/dH\n",
"#Results\n",
"print 'dH = %6.1f kJ'%(dH/1000)\n",
"print 'qp = %6.1f kJ'%(qp/1000)\n",
"print 'Error in calculations %4.1f'%(err*100)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"dH = 46.8 kJ\n",
"qp = 30.8 kJ\n",
"Error in calculations 34.3\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example Problem 3.9, Page Number 56"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"m = 124.0 #Mass of liquid methanol, g\n",
"Pi = 1.0 #Initial Pressure, bar\n",
"Ti = 298.0 #Intial Temperature, K\n",
"Pf = 2.5 #Final Pressure, bar\n",
"Tf = 425.0 #Intial Temperature, K\n",
"rho = 0.791 #Density, g/cc\n",
"Cpm = 81.1 #Specifi heat, J/(K.mol)\n",
"M = 32.04\n",
"\n",
"#Calculations\n",
"n = m/M\n",
"DH = n*Cpm*(Tf-Ti)+ m*(Pf-Pi)*1e-6/rho\n",
"\n",
"#Results\n",
"print 'Enthalpy change for change in state of methanol is %4.1f kJ'%(DH/1000)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Enthalpy change for change in state of methanol is 39.9 kJ\n"
]
}
],
"prompt_number": 8
}
],
"metadata": {}
}
]
}
|
