Final answer:
To predict how the rate of the reaction will change if the concentration of H₃CNH₂ is tripled, we must know the reaction order with respect to H₃CNH₂. If it is first-order, tripling the concentration will triple the rate; if it is second-order, it will increase the rate by a factor of nine.
Step-by-step explanation:
When the concentration of a reactant in a chemical reaction is changed, it affects the rate of the reaction. If we use the given reference that tripling the concentration of H₃CNH₂ would increase the reaction rate, we can compare it to a similar situation where doubling the concentration of HI increases the reaction rate quadruply because the reaction is second-order with respect to HI, shown as k[HI]².
If the reaction involving H₃CNH₂ is first-order, as is often the case when a direct proportionality is observed between concentration and rate, tripling the concentration of H₃CNH₂ would result in tripling the reaction rate. However, if the reaction is second-order or higher with respect to H₃CNH₂, then the reaction rate increase would be more than threefold. For example, if the reaction were second-order, the rate would increase by a factor of nine (3² = 9).
However, with the information given, we cannot definitively determine the exact increase in reaction rate without knowing the order of the reaction with respect to H₃CNH₂. We must therefore know the rate law for the overall reaction to accurately predict how the rate will change.