Chemical Mass Balances

2. Balances
B. Balance on Continuous Steady-State Processes

The following equation is for a continuous steady-state process, and because accumulation equals zero, it can be written as follows:
input+generation=output+consumption
If the previous balance is on a nonreactive species or on total mass, then it can be written as input=output because generation and consumption equals zero.

C. Integral Balances on Batch Processes

By using reasoning it can be said that
accumulation=final output-initial input
                            generation - consumption

Therefore, the following equation for a batch process is used:
initial input+generation=final output+consumption

Except for the input and output terms being changed to inititial and final amounts of the balanced substance than flow rates, this equation is identical to the equation of a continuous steady-state process.

D. Integral Balances on Semibatch and Continuous Processes

Integral balances can be written for continuous and semibatch processes, if the differential balance on the system is written and then integrated between two instances of time. Most problems of this type are often straightforward and easy to determine.