Question

Which is a reason to use rate laws?

to investigate how the pressure of liquids affects reaction rates
to find the new rate when the concentration of reactants changes
to calculate the molecular weight of compounds in a reaction
to find the number of moles of solute that are dissolved in 1 L of solution

Answer 1

The answer is B, to find the new rate when the concentration of reactants changes.

Hope this helps.

Answer 2

to find the new rate when the concentration of reactants changes

Step-by-step explanation:

The rate of a chemical reaction is the rate of change of concentration of reactants or products with time. As a reaction progresses the concentration of reactant decreases and the concentration of product increases. The rate law is the product of the rate constant and the molar concentration of the reactant(s) involved in the chemical reaction. Due to direct proportionality between rate law and concentration of reactants, the rate law is directly affected by the change in the concentration of the reactants.