The Fe 2 + ( 55.845 g/mol) content of a 2.349 g steel sample dissolved in 50.00 mL of an acidic solution was determined by tiration with a standardized 0.100 M potassium permanganate ( KMnO 4 , 158.034 g/mol) solution. The titration required 43.16 mL to reach the end point. What is the concentration of iron in the steel sample? Express your answer as grams of Fe per gram of steel. MnO − 4 + 8 H + + 5 Fe 2 + − ⇀ ↽ − Mn 2 + + 5 Fe 3 + + 4 H 2 O

0.513 iron per gram of steel is the concentration of iron in the steel sample.

Explanation:

Molarity of solution = 0.100 M

Volume of solution = 43.16 mL = 0.04316 L( 1mL=0.001 L)

Moles of = n

1 mole of gives 1 mole of potassium ion and manganate ions.

Moles of

According to reaction, 1 mole of manganate ion reacts with 5 moles of ferrous ions.Then 0.004316 mole of manganate ion will react with L:

of ferrous ions

Mass of 0.02158 moles of ferrous ion:

0.02158 mol × 55.845 g/mol = 1.2051 g

Mass of steel sample = 2.349 g

Concentration on iron in sample :

iron per gram of steel

- lead + phosphoric acid = hydrogen + lead(ii) phosphate