{ "metadata": { "name": "" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 16:Acid-Base Equilibria and Solubility Equilibria" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.1,Page no:715" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "InitCH3COOH1=0.2 #Initial concentration of CH3COOH solution, M\n", "#Let 'x' be the equilibrium concentration of the [H+] and [CH3COO-] ions after dissociation of [CH3COOH], M\n", "Ka=1.8*10**-5 #equilibrium constant of acid, M\n", "InitCH3COONa=0.3 #Initial concentration of CH3COONa solution and is equal to conc of Na+ and CH3COO- as it completely dissociates, M\n", "InitCH3COOH2=0.2 #Initial concentration of CH3COOH solution, M\n", "\n", "#Calculation\n", "#(a)\n", "import math\n", "x1=math.sqrt(Ka*InitCH3COOH1) #from the definition of ionisation constant Ka=[H+]*[CH3COO-]/[CH3COOH]=x*x/(0.2-x), which reduces to x*x/0.2, as x<<0.2 (approximation)\n", "pH1=-math.log10(x1) #since x is the conc. of [H+] ions\n", "\n", "#(b)\n", "#Let 'x' be the equilibrium concentration of the [H+] and hence conc of [CH3COO-] ions is '0.3 + x', M\n", "x2=Ka*InitCH3COOH2/InitCH3COONa #from the definition of ionisation constant Ka=[H+]*[CH3COO-]/[CH3COOH]=x*(0.3+x)/(0.2-x), which reduces to x*0.3/0.2(approximation)\n", "pH2=-math.log10(x2) #since x is the conc. of [H+] ions\n", "\n", "#Result\n", "print\"(a) the pH of CH3COOH solution is \",round(pH1,2)\n", "print\"(b) the pH of CH3COOH and CH3COONa solution is :\",round(pH2,2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "(a) the pH of CH3COOH solution is 2.72\n", "(b) the pH of CH3COOH and CH3COONa solution is : 4.92\n" ] } ], "prompt_number": 92 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 16.3,Page no:719" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "Ka=1.8*10**-5 #ionisation constant of acid\n", "InitCH3COONa=1 #Initial concentration of CH3COONa solution and is equal to conc of Na+ and CH3COO- as it completely dissociates, M\n", "InitCH3COOH=1 #Initial concentration of CH3COOH solution, M\n", "HCl=0.1 #moles of HCl added to 1L solution\n", "\n", "#Calculation\n", "import math\n", "#(a)\n", "x=Ka*InitCH3COOH/InitCH3COONa #from the definition of ionisation constant Ka=[H+]*[CH3COO-]/[CH3COOH]=x*(1+x)/(1-x), which reduces to x(approximation)\n", "pH=-math.log10(x) #since x is the conc. of [H+] ions\n", "#(b)\n", "CH3COO=InitCH3COONa-HCl #conc of CH3COO- ions, M\n", "CH3COOH=InitCH3COOH+HCl #conc of CH3COOH, M\n", "x2=Ka*CH3COOH/CH3COO #from the definition of ionisation constant Ka=[H+]*[CH3COO-]/[CH3COOH]=x*(0.9+x)/(1.1-x), which reduces to x*0.9/1.1(approximation)\n", "pH2=-math.log10(x2) #since x is the conc. of [H+] ions\n", "\n", "#Result\n", "print\"(a) the pH of CH3COOH and CH3COONa solution is :\",round(pH,2)\n", "print\"(b) the pH of solution after adding HCl is :\",round(pH2,2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "(a) the pH of CH3COOH and CH3COONa solution is : 4.74\n", "(b) the pH of solution after adding HCl is : 4.66\n" ] } ], "prompt_number": 93 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.5,Page no:728" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "InitCH3COOH=0.1 #Initial concentration of CH3COOH solution, M\n", "VCH3COOH=25 #volumeof CH3COOH, mL\n", "nCH3COOH=InitCH3COOH*VCH3COOH/1000 \n", "Ka=1.8*10**-5 #equilibrium constant of acid, M\n", "Kb=5.6*10**-10 #equilibrium constant of base, M\n", "N=0.1 #Initial concentration of NaOH solution, M\n", "V=10 #Initial volume of NaOH solution, mL\n", "\n", "\n", "#Calculation\n", "#(a)\n", "n=N*V/1000 #Initial moles of NaOH solution\n", "import math\n", "nCH3COOH_tit=nCH3COOH-n #moles of CH3COOH after titration\n", "nCH3COO=n #moles of CH3COO after titration\n", "H=nCH3COOH_tit*Ka/nCH3COO #conc of H+ ions, M\n", "pH=-math.log10(H) #since H is the conc. of [H+] ions\n", "\n", "#Result\n", "print\"(a) the pH of the solution is :\",round(pH,2)\n", "\n", "\n", "#Calculation\n", "#(b)\n", "V2=25.0 #Initial volume of NaOH solution, mL\n", "n2=N*V2/1000.0 #Initial moles of NaOH solution\n", "nCH3COOH_tit2=nCH3COOH-n2 #moles of CH3COOH after titration\n", "nCH3COO2=n2 #moles of CH3COO- ions after titration\n", "V_total=V2+VCH3COOH #total volume after titration\n", "CH3COO=nCH3COO2/V_total*1000 #conc of CH3COO- ions, M\n", "x=math.sqrt(Kb*CH3COO) #from the definition of ionisation constant Kb=[OH-]*[CH3COOH]/[CH3COO-]=x*x/(0.05-x), which reduces to x*x/0.05, as x<<0.05 (approximation)\n", "pOH=-math.log10(x) #since x is the conc. of [OH-] ions\n", "pH2=14.0-pOH \n", "\n", "#Result\n", "print\"(b) the pH of the solution is :\",round(pH2,2)\n", "\n", "#Calculation\n", "#(c)\n", "N=0.1 #Initial concentration of NaOH solution, M\n", "V=35 #Initial volume of NaOH solution, mL\n", "n=N*V/1000 #Initial moles of NaOH solution\n", "n_tit=n-nCH3COOH #moles of NaOH after titration\n", "nCH3COO=nCH3COOH #moles of CH3COO- ions after titration\n", "V_total=V+VCH3COOH #total volume\n", "OH=n_tit/V_total*1000 #conc of OH- ions, M\n", "pOH=-math.log10(OH) #since OH is the conc. of [OH-] ions\n", "pH=14-pOH \n", "\n", "#Result\n", "print\"(c) the pH of the solution is :\",round(pH,2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "(a) the pH of the solution is : 4.57\n", "(b) the pH of the solution is : 8.72\n", "(c) the pH of the solution is : 12.22\n" ] } ], "prompt_number": 94 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.6,Page no:730" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "InitNH3=0.1 #Initial concentration of NH3 solution, M\n", "VNH3=25 #volume of NH3, mL\n", "nNH3=InitNH3*VNH3/1000 \n", "Ka=5.6*10**-10 #equilibrium constant of acid, M\n", "N=0.1 #Initial concentration, M\n", "\n", "#Calculation\n", "import math\n", "V=VNH3/InitNH3*N #Initial volume, mL\n", "V_total=V+VNH3 #total volume of the mixture, mL\n", "n_NH4Cl=nNH3 #moles of NH4Cl\n", "NH4Cl=n_NH4Cl/V_total*1000 #conc of NH4+ ions formed, M\n", "x=math.sqrt(Ka*NH4Cl) #from the definition of ionisation constant Ka=[H+]*[NH3]/[NH4+]=x*x/(NH4+-x), which reduces to x*x/NH4+, as x<Ksp): #determination of precipitation\n", " print\"Q>Ksp, The solution is supersaturated and hence a precipitate will form\"\n", "else: \n", " print\"QKsp, The solution is supersaturated and hence a precipitate will form\n" ] } ], "prompt_number": 99 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.11,Page no:743" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "Br=0.02 #conc of Ag+ ions, M\n", "Ksp1=7.7*10**-13 #solubility product of AgBr\n", "Ksp2=1.6*10**-10 #solubility product of AgCl\n", "Cl=0.02 #conc of Cl- ions, M\n", "\n", "#Calculation\n", "#for Br\n", "Ag1=Ksp1/Br #conc of Ag+ ions at saturated state, M\n", "#for Cl\n", "Ag2=Ksp2/Cl #conc of Ag+ ions at saturated state, M\n", "\n", "#Result\n", "print \"[Ag+]=\",Ag2,\"M\"\n", "print\"To precipitate Br- without precipitating Cl- the concentration of Ag must be greater than %.1e\"%Ag1,\"M but less than\",Ag2,\"M\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "[Ag+]= 8e-09 M\n", "To precipitate Br- without precipitating Cl- the concentration of Ag must be greater than 3.9e-11 M but less than 8e-09 M\n" ] } ], "prompt_number": 100 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.12,Page no: 745" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "N_AgNO3=6.5*10**-3 #normality of AgNO3, M\n", "AgCl=143.4 #mol mass of AgCl, g\n", "Ksp=1.6*10**-10 #solubility product of AgCl\n", "\n", "#Calculation\n", "Ag=N_AgNO3 #conc of Ag+ ions as 's' is negligible, M\n", "s=Ksp/Ag #as Ksp=[Ag+][Cl-], molar solubility of AgCl, M\n", "solubility=s*AgCl #solubility of AgCl in AgBr solution, g/L\n", "\n", "#Result\n", "print\"The solubility of AgCl in AgBr solution is :%.2e\"%solubility,\"g/L\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The solubility of AgCl in AgBr solution is :3.53e-06 g/L\n" ] } ], "prompt_number": 101 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.14,Page no:748" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "FeCl2=0.003 #normality of FeCl2, M\n", "Fe=FeCl2 #as Fe2+ is strong electrolyte, conc of Fe2+=conc of FeCl2, M\n", "Ksp=1.6*10**-14 #solubility product of FeCl2\n", "Kb=1.8*10**-5 #ionisation constant of base\n", "\n", "#Calculation\n", "import math\n", "OH=math.sqrt(Ksp/Fe) #as Ksp=[Fe2+][OH-]**2, conc of OH- ions, M\n", "x=(OH**2)/Kb+OH #as Kb=[NH4+][OH-]/[NH3]\n", "\n", "#Result\n", "print\"To initiate precipitation the conc of NH3 must be slightly greater than :%.1e\"%x,\"M\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "To initiate precipitation the conc of NH3 must be slightly greater than :2.6e-06 M\n" ] } ], "prompt_number": 102 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.15,Page no:750" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "CuSO4=0.2 #normality of CuSO4, M\n", "NH3=1.2 #initial conc of NH3, M\n", "VNH3=1 #volume of NH3, L\n", "Kf=5*10**13 #formation constant\n", "\n", "#Calculation\n", "CuNH34=CuSO4 #conc of Cu(NH3)4 2+, M\n", "NH3=NH3-4*CuNH34 #conc of NH3 after formation of complex, as 4 moles of NH3 react to form 1 mole complex, M\n", "x=CuNH34/(NH3**4*Kf) #as Kf=[Cu(SO4)3 2+]/[Cu2+][NH3]**4\n", "\n", "#Result\n", "print\"The conc of Cu2+ ions in equilibrium is :%.1e\"%x,\"M\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The conc of Cu2+ ions in equilibrium is :1.6e-13 M\n" ] } ], "prompt_number": 103 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example no:16.16,Page no:751" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "InitNH3=1 #initial conc of NH3, M\n", "Ksp=1.6*10**-10 #solubility product of AgCl\n", "Kf=1.5*10**7 #formation constant of complex\n", "\n", "#Calculation\n", "K=Ksp*Kf #overall equilibrium constant\n", "import math\n", "s=math.sqrt(K)/(1+2*InitNH3*math.sqrt(K)) #molar solubility of AgCl, M\n", "\n", "#Result\n", "print\"Amount of AgCl which can be dissolved in 1 L of 1 M NH3 sol in equilibrium is :\",round(s,3),\"M\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Amount of AgCl which can be dissolved in 1 L of 1 M NH3 sol in equilibrium is : 0.045 M\n" ] } ], "prompt_number": 91 } ], "metadata": {} } ] }