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1, when 10.0 mL of 0.020 M IO_3, 30.0 mL of starch indicator, 10.0 ml of 0.0080

ID: 981521 • Letter: 1

Question

1, when 10.0 mL of 0.020 M IO_3, 30.0 mL of starch indicator, 10.0 ml of 0.0080 M HSO_3; and 50.0 are mixed, what is the molar concentration of HSO_3 in the resulting 100.0 mL of solution (before any occurs)? See the experiment on QUANTITATIVE SOLUTION PREPARATION earlier in the lab manual Chapter 4 (Section 4) in the lecture text, if you have forgotten how to do dilution calculations. The multiple trials of this reaction make it possible to write a rate equation that describes this reaction: Rate = k [IO_3 ]^3 [HSO_3 ]^n

Explanation / Answer

For Trial 1,

initial volume of [IO3-] = 10 ml of 0.02 M

moles of IO3- = 0.02 M x 10 ml = 0.2 mmol

final volume = 100 ml

final concentration of [IO3-] in 100 ml solution = 0.2 mmol/100 ml = 0.002 M

Similarly, for HSO3-,

initial volume HSO3- = 10 ml of 0.008 M

moles of HSO3- = 0.008 x 10 = 0.08 mmol

concentration [HSO3-] in 100 ml = 0.08/100 = 0.0008 M

We can do the restof calculations the same way,

Table filled :

Trial    V of IO3-   V of starch   V of HSO3-   V of H2O        Final [IO3-] M        Final [HSO3-] M

1            10               30                10                 50                   0.002                      0.0008

  2            15               30                10                 45                   0.003                      0.0008

  3            20               30                10                 40                   0.004                      0.0008

  4            30               30                10                 30                   0.006                      0.0008

  5            10               30                15                 45                   0.002                      0.0012

  6            10               30                20                 40                   0.002                      0.0016

  7            10               30                30                 30                   0.002                      0.0024