Question

In: Chemistry

Test tubes 1-8 contain the following amounts of 0.05M [KI] and 0.002M [I2]. The absorbance of...

Test tubes 1-8 contain the following amounts of 0.05M [KI] and 0.002M [I2]. The absorbance of the solutions were then measured at a wavelength of 430nm. Calculate the final [I2].

Test Tube 0.05 M KI (mL) 0.002M I2 (mL) Final [I2] Absorbance
1 10 0 0.0
2 8 2 0.369
3 6 4 0.631
4 4 6 0.781
5 3 7 0.847
6 2 8 0.914
7 1 9 0.966
8 0 10 1.023

Solutions

Expert Solution

To calculate final I2 concentration, the following formula will be used:

M1V1 = M2V2

M1 = molarity of I2 initially = 0.002 M

V1 = volume of 0.002 M I2 used (given in table)

M2 = final concentration of I2 (to be found out)

V2 = final volume. In all the cases, it is 10 ml, which is made by mixing KI and I2.

For example in test tube 1,

M1V1 = M2V2

0.002*0 = M2*10

M2 = 0 M

Similarly other concentrations can be calculated.

Test Tube 0.05 M KI (mL) 0.002M I2 (mL) Final [I2] Absorbance
1 10 0 0 0.0
2 8 2 0.0004 0.369
3 6 4 0.0008 0.631
4 4 6 0.0012 0.781
5 3 7 0.0014 0.847
6 2 8 0.0016 0.914
7 1 9 0.0018 0.966
8 0 10 0.0020 1.023

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