Question

Table 1. Volumes of Solutions (mL) for Expirements 1 - 6.

Expirement	0.20 M NaI	0.20 M NaCl	0.010 M Na2S2O3	2% Starch	0.20 M K2SO4	0.20 M K2S2O8
1	2.00	2.00	2.00	1.00	2.00	2.00
2	2.00	2.00	2.00	1.00	0	4.00
3	4.00	0	2.00	1.00	2.00	2.00
4 (35˚C)	2.00	2.00	2.00	1.00	2.00	2.00
5 (10˚C)	2.00	2.00	2.00	1.00	2.00	2.00
6 (catalyst)	2.00	2.00	2.00	1.00	2.00	2.00

Use the information from Table 1 to calculate the molarity of S₂O₈^2- and the molarity of I^- in the test tubes for reactions 1 - 6. Hint: This is a dilution problem

Please show all work! Thank You.

Answer 1

Find the total volume of the solutions in test tube 1 = (2.00 + 2.00 + 2.00 + 1.00 + 2.00 + 2.00) mL = 11.0 mL.

Note that the final volume of the solutions is the same (=11.0 mL) in all the test tubes marked 2-6.

Work out the calculation for test tube 1 as a trial. Use the dilution equation.

M₁*V₁ = M₂*V₂ where V₁ = volume of stock solution added; V₂ = final volume of the solutions in all the test tubes (=11.0 mL); M₁ = concentration of stock solution and M₂ = concentration of the reagent in the final solution.

Start with S₂O8^2- as shown below.

(2.00 mL)*(0.20 M) = (11.0 mL)*M₂

===> M₂ = (2.00*0.20 M)/(11.0) = 0.036 M (round off till the third decimal place.)

Next work with I^- as shown below.

(2.00 mL)*(0.20 M) = (11.0 mL)*M₂

===> M₂ = (2.00*0.20 M)/(11.0) = 0.036 M (round off till the third decimal place.)

Treat the above two as sample calculations and work out the rest. Use the following data to present your data.

Experiment	Vol. of 0.20 M K2S2O8 added (mL)	Vol. of NaI added (mL)	Concentration of S2O82- in the final solution (M)	Concentration of I- in the final solution (M)
1	2.00	2.00	0.036	0.036
2	4.00	2.00	0.073	0.036
3	2.00	4.00	0.036	0.073
4	2.00	2.00	0.036	0.036
5	2.00	2.00	0.036	0.036
6	2.00	2.00	0.036	0.036