The initial concentration of an enzyme is 5 moles (mol). Twenty seconds into the reaction, only 0.4 $\mathrm{mol}$ of the enzyme remains. Find the rate of change of the enzyme in $\mathrm{mol} / \mathrm{s}$.
A) $0.23 \mathrm{~mol} / \mathrm{s}$
B) $-0.23 \mathrm{~mol} / \mathrm{s}$
C) $-4.35 \mathrm{~mol} / \mathrm{s}$
D) $4.35 \mathrm{~mol} / \mathrm{s}$

Question

Quizplus · Accepted Answer

The rate of change is found by dividing the change in concentration by the change in time. The enzyme concentration decreases by $5 \mathrm{mol} - 0.4 \mathrm{mol} = 4.6 \mathrm{mol}$ over 20 seconds, so the rate is $-4.6 \mathrm{mol} / 20 \mathrm{s} = -0.23 \mathrm{mol} / \mathrm{s}$, indicating a decrease in concentration over time.

The Initial Concentration of an Enzyme Is 5 Moles (Mol) mol\mathrm{mol}mol

The Initial Concentration of an Enzyme Is 5 Moles (Mol) $\mathrm{mol}$