A molecule of ethyl alcohol is converted to acetaldehyde in one's body by zero order kinetics. If the concentration of alcohol is 0.015 mol/L and the rate constant = 6.4 x 10-5 mol/L•min, what is the concentration of alcohol after 3.5 hours? (1) 0.0016 mol/L (2) 9.6 x 107 mol/L (3) 4.3 x 10-3 mol/L (4) 0.15 mol/L (5) 0.0032 mol/L

(1) 0.0016 mol/L

Explanation:

Let the concentration of alcohol after 3.5 hours be y M

The reaction follows a first-order

Rate = ky^0 = change in concentration/time

k = 6.4*10^-5 mol/L. min

Initial concentration = 0.015 M

Concentration after 3.5 hours = y M

Time = 3.5 hours = 3.5*60 = 210 min

6.4*10^-5y^0 = 0.015-y/210

y^0 = 1

0.015-y = 6.4*10^-5 * 210

0.015-y = 0.01344

y = 0.015 - 0.01344 = 0.00156 = 0.0016 mol/L (to 4 decimal places)