Question

The reaction will remove Arsenic concentration from water by promoting the precipitation of arsenic with sulfate to form a mineral. Sulfate concentration in the solution is 2.5 M (remains constant throughout the reaction) but the change of As concentration with time is shown in the table below.

• order of the reaction?  rate constant? 
• How long will it take to decrease the arsenic concentration below New Jersey drinking water standard of 5 µg/L?

(Please include the units as well.)

Time (min)	[As] (µg/L)
0	350
10	300
20	287
30	200
50	150
70	100
90	50
110	25
130	20
150	12
200	8
250	3
300	2
360	1