Redox stoich: the concentration of a tin(ll) chloride solution prepared from a sample of tin ore?

Problem

What is the concentration of a tin(ll) chloride solution prepared from a sample of tin ore?

Experimental Design

The potassium dichromate solution is first standardized by titration with 15.00 mL of an acidified 0.07 mol/L solution of the primary standard, iron(II) ammonium sulfate-6-water.  The standardized dichromate solution is then titrated against a sample of the acidified tin(II) chloride solution (You will do this step in the next question).

Evidence

 

TITRATION OF IRON(lI) SOLUTION

(volume of K2Cr2O7(aq) required to react with 15.00 ml of 0.07 mol/L Fe2+(aq))

 

Trial

1

2

3

4

Final buretreading(ml)     

13.8

24.4

35.2

45.9

Initial buretreading (ml)     

2.3

13.8

24.4

35.2

Find the concentration of the Cr2O72-(aq) in mol/L:  (give your answer to 4 decimal places)

Your Answer?