2Cu 2 4KI 2CuI I 2 4K (rxn 1) I 2 2Na 2 S 2 O 3 2NaI Na ...

2Cu 2 4KI 2CuI I 2 4K rxn 1 I 2 2Na 2 S 2 O 3 2NaI Na 2 S 4 O 6 rxn 2 Calculating m ....

2Cu2+ + 4KI â†’ 2CuI + I2 + 4K+ (rxn 1) I2 + 2Na2S2O3 â†’ 2NaI + Na2S4O6 (rxn...

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Chemistry

2Cu²⁺+ 4KI â†’ 2CuI + I₂+ 4K⁺ (rxn 1)

I₂ + 2Na₂S₂O₃ â†’ 2NaI +Na₂S₄O₆ (rxn 2)
10.0 mL of a Cu²⁺ solution of unknown concentrationwas placed in a 250 mL Erlenmeyer flask. An excess of KI solutionwas added. Indicator was added and the solution was diluted withH₂O to a total volume of 75 mL. The solution wastitrated with 0.20 M Na₂S₂O₃. Theequivalence point of the titration was reached when 14.45 mL ofNa₂S₂O₃ had been added. What isthe molar concentration of Cu²⁺ in the unknownsolution?

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3.9 Ratings (619 Votes)

2Cu²⁺ + 4KI â†’ 2CuI + I₂ + 4K⁺ (rxn 1)

I₂ + 2Na₂S₂O₃ â†’ 2NaI + Na₂S₄O₆ (rxn 2)

Calculating moles of thiosulphate =molarity *volume

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â = 0.20 mol per L*0.01445 L per mole

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â =0.00289moles

Calculating moles of I2=0.00289 mole of Na2S2O3*1mole I2/2 mole Na2S2O3

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â =0.001445 mole of I2

Calculating moles of Cu^2+=0.001445 mole of I2*2 mole of Cu^2+/1 mole of I2

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â =0.00289 mole of Cu2+

Molarity of the Cu2+=Moles/Volume in L

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â =0.00289 mole/0.010 L

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â =0.289 Molar

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