3.1.A general mass balance of the reactor Time Ut+At slope= dy/dt ←—△t→ t+△t Euler's method to solve a first order differential equation to calculate how the variable y varies with time t.Initial values ofy and t must be known.The t-scale is then divided into very small intervals(At) so that the slope dy/dt can be condidered practically constant in the interval t to t+At.The value ofy at the end of this interval is then obtained as yt+At=yt+t*dy/dt.The new values tAt and ytAt are then used as initial values for the next calculation.The time interval illustrated in the figure above is oversized.For simulation of a typical batch process the time interval is usually in the range of one second or below 3.1. A general mass balance of the reactor