The Conversion of Sucrose (Table Sugar) to Glucose and Fructose

The conversion of sucrose (table sugar) to glucose and fructose is first order in the concentration of sucrose, which means that the rate of reaction is proportional to the concentration of the sucrose. The rate of disappearance of sucrose can be expressed as , where c represents the concentration of the sucrose, and k is called the rate constant and is mathematically identical to the negative of the decay constant. If the rate constant is 0.20 hour^-1, how long will it take for the sucrose concentration to diminish to 1/80 of its initial concentration?

A) 21.91 hours
B) 0.020 hours
C) 400.00 hours
D) 128.76 hours