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# Given that the rate of a reaction depends on temperature, concentration, pressure and volume, which of the following is true?

$(1) \text{ Volume} \propto \large\frac{1}{\text{Rate}}$

$(2) \text{ Concentration} \propto \large\frac{1}{\text{Rate}}$

$(3) \text{ Pressure} \propto \large\frac{1}{\text{Rate}}$

$(4) \text{ Catalysts} \propto \large\frac{1}{\text{Rate}}$

$\begin{array}{1 1} (2) \;and \;(4) \\ Only (1) \\ Only (4) \\ (2) \;and (3)\end{array}$

Answer: Only $(1) \text{ Volume} \propto \large\frac{1}{\text{Rate}}$
Increase in concentration accelerates the rate. If the reactants are solid or liquid, effect on pressure is very little. If they are gases, an increase in pressure increases the concentration and therefore the rate. Therefore (2) and (3) are incorrect.
However, this means that since Volume is inversely proportional to Pressure, Volume is inversely proportional to the rate Therefore (1) is correct..
Generally catalysts increase the rate of reactions, however, some can decrease the rate also. Its not conclusive. Therefore (4) is incorrect.
Hence the answer is $(1) \text{ Volume} \propto \large\frac{1}{\text{Rate}}$
edited Jul 26, 2014