Breathalyzer lab titration problem

[magikalcb]

Given:

 

1) 2K2Cr2O7 + 8H2SO4+3C2H5OH --->2Cr2(SO4)3+2K2SO4+

3 CH3COOH + 11 H2O

 

2) K2Cr2O7 + 6 KI + 7 H2SO4 ---> Cr2(SO4)3 + 4 K2SO4 + 3 I2 +7H2O

 

3) I2 + 2 Na2S2O3 ---> 2 NaI + Na2S4O6

 

10mL of 0.0025 M K2Cr2O7

Initial Volume of Na2S203 25mL of .0010M Na2S203

final volume of Na2S203 12.39mL of .0010M Na2S203

 

 

How many moles of Na2S2O3 reacted in reaction 3.

How many moles of K2Cr2O7 that reacted with the ethanol in reaction 1.

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