Question

The rate constant for this first-order reaction is 0.064 at 400°C. After how many seconds will 19.2% of the reactant remain?

a) 50 seconds
b) 100 seconds
c) 150 seconds
d) 200 seconds

Answer 1

To determine the time it takes for 19.2% of the reactant to remain in a first-order reaction, we can use the equation t = ln(A / A0) / -k, where A is the final amount, A0 is the initial amount, k is the rate constant, and t is time. By plugging in the values given, we find that it will take 150 seconds for 19.2% of the reactant to remain.

Step-by-step explanation:

To determine the time it takes for 19.2% of the reactant to remain, we need to use the equation for first-order reactions. The equation is: ln(A / A0) = -kt, where A is the final amount, A0 is the initial amount, k is the rate constant, and t is time. Rearranging the equation to solve for t, we get: t = ln(A / A0) / -k. Plugging in the values, we have: t = ln(0.192 / 1.00) / -0.064 = 150 seconds. Therefore, the answer is c) 150 seconds.