Dr Iskanderani Fall ChE 201 Section 3 Material Balance Material Balance: is accounting of material is normally carried around a system What is a system? : It is a portion or whole of a process (or a plant) to be analyzed. What is a process? : It is one action or a series of actions or operations or treatments that result in an end.

2 BANK ACCOUNT MONEY BALANCE On 10/8/1426 Ali has SR 5,000 in his account in the bank On 25/8/1426 The bank deposited to his account SR 990 (his monthly salary) On 28/8/1426 He paid by telephone from his account for his mobile tel bill (SR ) He also paid for his home electric bill (SR ) He received a check from his friend for a loan he gave to him(SR 500) WHAT IS THE BALANCE OF HIS ACCOUNT as of 28/8/1426?

3 BANK ACCOUNT MONEY BALANCE ALI ’ s ACCOUNT SR SR SR SR SR 500 BALANCE = – – = SR

Dr Iskanderani Fall BANK ACCOUNT MONEY BALANCE ALI ’ s ACCOUNT SR SR SR SR SR 500

Dr Iskanderani Fall BANK ACCOUNT MONEY BALANCE ALI ’ s ACCOUNT SR 5000 SR 990 SR 500 SR SR BALANCE = – – = SR ACCUMULATION = – – = SR

Dr Iskanderani Fall Examples of operations: Example Type Fluid transport (in a pipe )Physical change Heat transportPhysical change Distillation columnPhysical change Chemical reactionChemical change DryingPhysical change Filling a tank of waterPhysical change MixingPhysical change

Dr Iskanderani Fall For Systems: We must define the boundary of the system Systems are 2 types : closed and open Closed system : material is not crossing the boundary Open system: material is crossing the boundary

Dr Iskanderani Fall Examples Closed ? Or open ? Distillation Column Water Tank

Dr Iskanderani Fall MB around a system : we apply the Law of conservation of mass Material Input - material output = Accummulation Example of accummulation - ve accummulaion+ve accummulation At steady state, variables do not change with time ; and the eq becomes: Material Input = material Output In this course (and in most processes), systems are at steady state Let ’ s explain steady state

Dr Iskanderani Fall WHAT WILL HAPPEN TO THE LEVEL OF WATER IN THE TANK BY TIME? 7000 kg Water Tank 100 kg/min IT WILL NOT CHANGE WITH TIME WE CALL IT STEADY STATE

Dr Iskanderani Fall WHAT WILL HAPPEN TO THE LEVEL OF WATER IN THE TANK after 5 minutes? 7000 kg Water Tank 60 kg/min 200 kg/min

Dr Iskanderani Fall kg Water Tank 80 kg/min 200 kg/min The System CHANGED WITH TIME WE CALL IT UNSTEADY STATE After 5 minutes

Dr Iskanderani Fall  If we have no reaction,the MB equation can be put as: Mass In = Mass out And also, Moles in = Moles out WHY? at steady state

Dr Iskanderani Fall  If we have no reaction,the MB equation can be put as: Mass In = Mass out And also, Moles in = Moles out WHY? at steady state

Dr Iskanderani Fall  If we have no reaction,the MB equation can be put as: What goes in must come out Mass in = mass out Moles in = Moles out Accumulation = 0 at steady state no reaction

Dr Iskanderani Fall Batch System Initial state 9000 kg 100% H 2 O 1000 kg 100% NaOH Final state 10,000 kg 90% H 2 O 10% NaOH System boundry

Dr Iskanderani Fall Batch System 9000 kg 100% H 2 O 1000 kg 100% NaOH 10,000 kg 90% H 2 O 10% NaOH Batch system represented as an open system System boundry

Dr Iskanderani Fall HCl ? H2SO4 ? H2O ?

Dr Iskanderani Fall HCl ? H2SO4 ? H2O ?

Dr Iskanderani Fall HCl ? H2SO4 ? H2O ?

Dr Iskanderani Fall HCl ? H2SO4 ? H2O ?

Dr Iskanderani Fall NOTE : If we divide by MWt, then the equations become also valid for moles.  Remember : no reaction here

Dr Iskanderani Fall

Dr Iskanderani Fall SOLVE A = 968.4kg and B = 31.6 kg How many equations have we used? How many equations are available ? Are they all independent? How many components do we have in the problem? Number of independent equations = no. of components in the system