Final answer:
The ∆[reactant]/∆t is always positive when calculating a reaction rate. Chemists follow the convention of expressing all reaction rates as positive numbers, but a negative sign is inserted to convert that expression to a positive number. Reaction rates generally decrease with time as reactant concentrations decrease.
Step-by-step explanation:
The ∆[reactant]/∆t is always positive when calculating a reaction rate.
Chemists follow the convention of expressing all reaction rates as positive numbers. However, a negative sign is inserted in front of A[A]/At to convert that expression to a positive number.
Reaction rates generally decrease with time as reactant concentrations decrease.