HOW CAN THIS BE DONE ..

Question

REGARDING THIS QUESTION : IF THE RATE CONSTANT FOR THE ABOVE REACTION AT 35 DEG C WAS 6.2 X 10^-5 PER SECOND AND THE INITIAL SUCROSE CONCENTRATION WAS 0.4 , WHAT WILL IT'S CONCENTRATION WILL BE AFTER 2 HOURS ???

HOW CAN THIS QUESTION COULD BE SOVED

??? WHICH LAW CAN I USE

Answer 1

The clue is the units of the rate constant: reciprocal time. This means the reaction obeys first order kinetics, and we can use the integrated form of the first order rate law:

ln[A] = -kt + ln[A]o,

where [A] is sucrose concentration. Just substitute:

ln[A] = -(6.2x10^-5 /sec) (2*60*60 sec) + ln(0.4 M)

Solving, [A] = 0.26 M