Two chemicals are mixed together and a gas is produced. *
chemical change
physical change ​

chemical change

Explanation:

chemical change is when a substance combine with another substance to form a new substance.

(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)