To obtain the rate of the reaction
3I-(aq) + H3AsO4(aq) + 2H+(aq) --> I3-(aq) + H3AsO3(aq) + H2O (l)
I got that the rate is
1/3 delta [I-]/ delta t = delta [H3AsO4]/ delta t
is this correct
To determine the rate of a chemical reaction, you need to consider the changes in concentration of the reactants or products over time. The rate is expressed as the change in concentration (Δ[A]) divided by the change in time (Δt) for any reactant or product involved in the reaction.
In your given reaction:
3I-(aq) + H3AsO4(aq) + 2H+(aq) --> I3-(aq) + H3AsO3(aq) + H2O(l)
You correctly identified that the rate is given by the change in concentration of iodide ions (I-) over time (Δ[I-]) divided by the change in time (Δt):
Rate = Δ[I-] / Δt
However, your statement that the rate is equal to the change in concentration of the arsenic acid (H3AsO4) over time (Δ[H3AsO4] / Δt) is not entirely accurate. The rate is specifically determined by the change in concentration of each reactant or product, not just a single reactant.
To fully determine the rate of the reaction, you would need to consider the change in concentration of all the reactants included in the balanced equation. In this case, you would need to determine the changes in concentrations of both iodide ions (Δ[I-]) and arsenic acid (Δ[H3AsO4]), divided by the change in time (Δt):
Rate = (1/3) * Δ[I-] / Δt = Δ[H3AsO4] / Δt
So, in summary, your original equation is not entirely correct. The rate of the reaction involves considering the changes in concentration of all relevant reactants and products, not just a single reactant.