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Varying Concentrations of 1.0 M HCl. Varying Concentrations of 0.3 M Na_2S_2O_3.

ID: 1056522 • Letter: V

Question

Varying Concentrations of 1.0 M HCl. Varying Concentrations of 0.3 M Na_2S_2O_3. Determine the rate law for the reaction you observed. You will need to either calculate, as described in the lab write up, or by inspection as described in the module. The reaction rate order for each reactant needs to be figured out as well as the value for the constant, k. Using the rate law that you determined for the reaction above, predict the rate of the reaction if the concentration of HCl was changed to 0.20M and the concentration of Na_2S_2O_3 is 0.30M. This is a calculation that should result in one answer; rate = ####. SHOW YOUR WORK Using the following rate law, and the experimental values given, calculate k:

Explanation / Answer

From the given data

A. when the concentration of HCl was changed, the rate did not change. So rate is independent of HCl concentration

When the concentration of Na2S2O3 is doubled, the rate also doubled,

So the rate law becomes,

rate = k[Na2S2O3]^2

B. k = 0.0166/(0.045)^2 = 8.20 M-1.s-1

when [Na2S2O3] = 0.3 M

rate = 8.20 x (0.3 x 0.3) = 0.738 M/s

C. k = 8.20 M-1.s-1