A)In the experiment, you will be measuring the time it takes for the solution to

Question

A)In the experiment, you will be measuring the time it takes for the solution to turn blue. If you have initial concentrations of I- = 0.022 M, BrO3- = 0.013 M, H+ = 1.8 x 10-5 M, and S2O32- = 0.007 M, what is the concentration of S2O32- when the solution turns blue?

B)In the experiment, you will be measuring the time it takes for the solution to turn blue. If you have initial concentrations of I- = 0.023 M, BrO3- = 0.023 M, H+ = 1.8 x 10-5 M, and S2O32- = 0.006 M, what is the concentration of I- when the solution turns blue?

C)An experiment is run and found to obey the rate law rate = kX2Y. Additionally, it is found that it has an activation energy of 170,821 J/mol. If the rate constant for the reaction is 2.5 x 10-2 M-2s-1at 267 oC, what is the rate constant at 235 oC?

Explanation / Answer

Part A) At first, the I2 produced by reaction [2] is gobbled up by the thiosulfate as fast as it is made, The products of this reaction are colorless – you can’t see them. However, once the thiosulfate is used up, the concentration of I2 is free to react with starch, forming a starch complex you can see (it’s deep blue). So concetration of S2O32-=0M when solution turns blue.

6 I-(aq) + BrO3 -(aq) + 6 H+(aq)----> 3 I2(aq) + Br-(aq) + 3 H2O [1]

I2(aq) + 2 S2O3 2-(aq)-----> 2 I-(aq) + S4O6 2-(aq) [2]

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