Calculating the rate of disappearance of HCl
The rate of disappearance of HCl was measured for the following reaction:

CH3OH(aq) + HCl(aq) - CH3Cl(aq) + H2O(l)

The following data were collected:

Time (Min) [HCl] (M)
i. 0.0 1.85
ii. 54.0 1.58
iii. 107.0 1.36
iv. 215.0 1.02
v. 430.0 0.580

a. Calculate the average rate of reaction, in M/s, for the time interval between each measurement.
b. Graph HCl versus time, and determine the instantaneous rates in M/min at t=75.0 min and t=250 min.