Reference no: EM132688778

1. Potassium dichromate reacts with potassium oxalate according to the equation: 3K2C2O4(aq) + K2Cr2O7(aq) + 8H+ (aq) → 6CO2(g) + Cr2O3(s) + 4H2O(l) + 8K+(aq) When 0.2016 g of anhydrous potassium oxalate was dissolved in dilute acid and titrated with a solution of potassium dichromate, the volume required to reach the endpoint was 17.97 mL. Calculate the concentration of the potassium dichromate solution.

2. 1.145 g of sodium chloride and 1.285×10-2 mol of sodium peroxydisulfate (Na2S2O8) were mixed together and ground in a mortar and pestle. Calculate the percent by mass of sodium chloride in the resulting mixture.

3. The potassium dichromate solution from question 1 was used to titrate a sample known to contain a mixture of sodium sulfate and sodium oxalate (which reacts just like potassium oxalate). The dichromate does not react with sodium sulfate. 0.2487g of the mixture was dissolved in dilute acid and titrated with the potassium dichromate solution to an endpoint at 12.61 mL. Calculate the percent by mass of sodium oxalate in the unknown mixture.

4. To prepare for the lab, balance and combine each of the following oxidation half reactions with the permanganate reduction half reaction. Permanganate half reaction: MnO4 - (aq) + 8H+(aq) + 5e- → Mn2+(aq) + 4H2O(l) Iron(II) oxidation half reaction: Fe2+(aq) → Fe3+(aq) + e

Combined balanced reaction:

Dihydrogen phosphate oxidation half reaction: H2PO3 - (aq)+H2O(l) → H3PO4(aq) + H+ (aq) + 2 e

Combined balanced reaction:

Formate ion oxidation half reaction: HCOO- (aq) → CO2(g) + H+(aq) + 2 e-

Combined balanced reaction:

Tin(II) oxidation half reaction: Sn2+(aq) → Sn4+(aq) + 2 e-

Combined balanced reaction: