3. A chemical spill releases 55 gallons of 5 Molar sodium cyanide into a river over a period of 45 minutes. The river channel is 25 m Wide and 2 m deep (assume rectangular) with a ow velocity of 0.8 m/s. To calculate the initial concentration. assume that total mass of spilled cyanide mixes with the volume of water that ows past during the spill. A) What is the initial concentration? B) The cyanide is lost from the river with a rate constant of0.05 hr'l. The longitudinal dispersion coefficient is 30 1115's. What would be the maximum concentration of the plume 5 km downstream from the spill? C) How long would it take the plume to reach this location? (See example problem 4.8)