Since a balanced process can always be scaled, material balance calculations can be performedon the basis of any convenient set of stream amounts or flow rates and the results can afterwardbe scaled to any desired extent. A basis of calculation is an amount (mass or moles) or flow rate(mass or molar) of one stream or stream component in a process. The first step in balancinga process is to choose a basis of calculation; all unknown variables are then determined to beconsistent with this basis.If a stream amount or flow rate is given in a problem statement, it is usually most convenientto use this quantity as a basis of calculation. If no stream amounts or flow rates are known, assumeone, preferably that of a stream with a known composition. If mass fractions are known, choosea total mass or mass flow rate of that stream (e.g., 100 kg or 100 kg/h) as a basis; if mole fractionsare known, choose a total number of moles or a molar flow rate.1. What is a balanced process? How do you scale a flowchart? What is a basis of calculation?2. The processes shown below were balanced using the indicate bases of calculation. Scaleas directed, and draw flowcharts for the scaled processes.(a) Mix C₂H6 with air. Basis of calculation: 100 mol C₂H6.ntals of Material BalancesScale up to a feed of 1000 kmol C₂H6/h.100 mol C₂H62000 mol air0.21 mol O₂/mol0.79 mol N₂/mol(b) Distill a benzene-toluene mixture. Basis: 1 g feed.1g0.600 g C₂H₂0.400 g C₂H₂al Mass Balance:zene Balance:0.500 g0.300 g C6H6/g0.700 g C₂Hg/gScale up to a flow rate of 100 lbm/min of the upper product stream.esspose 3.0 kg/min of benzene and 1.0 kg/min of toluene are mixed. The process flowchartht be drawn and labeled as follows:3.0 kg C6H6/min1.0 kg C7Hg/minre are two unknown quantities-m and x-associated with the process, so two equationsneeded to calculate them.3.0156 lb-moles A/h469 lb-moles B/h.Material balance equations for this nonreactive process all have the simple form input =put. Three possible balances can be written on total mass, benzene, and toluene-any twowhich provide the equations needed to determine m and x. For example,3.0kgmin+1.0kg C6H6min2100 mol0.0476 mol C₂Hg/mol0.200 mol O₂/mol0.752 mol N₂/mol0.500 g0.900 g C6H6/g0.100 g C₂H₂/g=kgminm(kg/min)x(kg C6H6/kg)(1-x)(kg C7Hg/kg)= m = in = 4.0 kg/min11m m 40 kg/min=m(kg) x(kg C6H6)(min)(kg)

Question

Since a balanced process can always be scaled, material balance calculations can be performedon the basis of any convenient set of stream amounts or flow rates and the results can afterwardbe scaled to any desired extent. A basis of calculation is an amount (mass or moles) or flow rate(mass or molar) of one stream or stream component in a process. The first step in balancinga process is to choose a basis of calculation; all unknown variables are then determined to beconsistent with this basis.If a stream amount or flow rate is given in a problem statement, it is usually most convenientto use this quantity as a basis of calculation. If no stream amounts or flow rates are known, assumeone, preferably that of a stream with a known composition. If mass fractions are known, choosea total mass or mass flow rate of that stream (e.g., 100 kg or 100 kg/h) as a basis; if mole fractionsare known, choose a total number of moles or a molar flow rate.1. What is a balanced process? How do you scale a flowchart? What is a basis of calculation?2. The processes shown below were balanced using the indicate bases of calculation. Scaleas directed, and draw flowcharts for the scaled processes.(a) Mix C₂H6 with air. Basis of calculation: 100 mol C₂H6.ntals of Material BalancesScale up to a feed of 1000 kmol C₂H6/h.100 mol C₂H62000 mol air0.21 mol O₂/mol0.79 mol N₂/mol(b) Distill a benzene-toluene mixture. Basis: 1 g feed.1g0.600 g C₂H₂0.400 g C₂H₂al Mass Balance:zene Balance:0.500 g0.300 g C6H6/g0.700 g C₂Hg/gScale up to a flow rate of 100 lbm/min of the upper product stream.esspose 3.0 kg/min of benzene and 1.0 kg/min of toluene are mixed. The process flowchartht be drawn and labeled as follows:3.0 kg C6H6/min1.0 kg C7Hg/minre are two unknown quantities-m and x-associated with the process, so two equationsneeded to calculate them.3.0156 lb-moles A/h469 lb-moles B/h.Material balance equations for this nonreactive process all have the simple form input =put. Three possible balances can be written on total mass, benzene, and toluene-any twowhich provide the equations needed to determine m and x. For example,3.0kgmin+1.0kg C6H6min2100 mol0.0476 mol C₂Hg/mol0.200 mol O₂/mol0.752 mol N₂/mol0.500 g0.900 g C6H6/g0.100 g C₂H₂/g=kgminm(kg/min)x(kg C6H6/kg)(1-x)(kg C7Hg/kg)= m => in = 4.0 kg/min11m m 40 kg/min=m(kg) x(kg C6H6)(min)(kg)

Accepted Answer

Amount of C2H6 = 100 mol
Amount of air = 2000 mol
Amount of benzene-toluene mixture = 1 g