Question

The amount of iron in steel can be determined by titration with dichromate. First, the steel is dissolved in hydrochloric acid to oxidize all the iron to Feat. An indicator is added that will react with excess dichromate. Then, potassium dichromate is added to the solution until the end point is reached. Cr, 02- +6Fe2+ + 14H+ > 2Cr3+ +6Fe3+ + 74,0 For the analysis of 2.00 g of steel, the titration required 22.70 mL of 0.1800 M K2Cr207. What was the mass percentage of iron in this steel sample? Number

Answer 1

Answers Gilien, 0.00g of steel, of steel, the titration the a of 2.00g analysis o for the required 2270 ml of 0.1800 M K₂ (2207. Here, we have to of iron in this steel find the mass percentage sample - let, of K₂ ( Of = 0.1800 X 22.70mlx- '1ooomL Moles -0.00 h086 mol K₂ Cr 2 Oz (aq) + 6F (2+ (aq) +144+ (aq). → 2673+(aq) +6Festlaq) + 2K+ (aq) + 7 Heolil Moles of Feet = 0.004086 mol KC1207* 6 mol Felt Imolkzlr₂07 -0.0245/6 mol Felt Mass of iron -0.024516 mol x55.86 = 1.379 Therefore,

mass percentage of iron = 1379 xloo 2.00g 6 0.685 x loo = 68.5.1. Therefore, The mass percentage of iron is (68.5%)