v ferrous sulfate is the chemical compound with

v ferrous sulfate is the chemical compound with the formula Fe. SO 4. Its molecular weight 278. 05, melting point 329. 9ºC. It has a pale green color as a powder, and as crystals it has a bluish green color, freely soluble in water. v The medical uses: • It is used medically to treat iron deficiency • Together with other iron compounds, ferrous sulfate is used to fortify foods and to treat iron-deficiency anemia.

v side effect of ferrous sulfate tablets: Constipation is a frequent and uncomfortable side effect associated with the administration of oral iron supplements. Stool softeners often are prescribed to prevent constipation. v Chemical principle: In acidic solution, potassium permanganate rapidly and quantitatively oxidizes iron(II) to iron(III), while itself being reduced to manganese(II). The half reactions for the process are:

When these half-reactions are combined to give the overall balanced chemical reaction equation, a factor of five must be used with the iron half-reaction so that the number of electrons lost in the overall oxidation will equal the number of electrons gained in the reduction The complete molecular equation should be: 10 Fe. SO 4 + 2 KMn. O 4 + 8 H 2 SO 4 5 Fe 2(SO 4)3 + K 2 SO 4 + 2 Mn. SO 4 + 8 H 2 O

Procedure: 1. Carefully crush one tablet of ferrous sulfate (Use a mortar and pestle ) transfer in a beaker , Add 15 ml of distilled water and stir to dissolve the solid. 2. Add 8 ml of 3 N sulfuric acid, H 2 SO 4 , to the sample and carefully filter the sample 3. Titrate with Potassium Permanganate Solution to the endpoint. The end point is the first appearance of a permanent, pale pink color.

Calculation: 1 eq. S of KMn. O 4 ≡ 1 eq. S of Fe. SO 4 1 L 1 N KMn. O 4 ≡ ( Wt/eq. Wt. ). Fe. SO 4 1 L 1 N KMn. O 4 ≡ 278. 05 g/eq. Fe. SO 4 1000 ml 1 N KMn. O 4 ≡ 278. 05 g/eq. Fe. SO 4 1000 1 ml 1 N KMn. O 4 ≡ 0. 27805 g/eq. Fe. SO 4

Notes: § Potassium permanganate is one of the most commonly used oxidizing agents because it is extremely powerful, inexpensive, and readily available. § Potassium permanganate is particularly useful among titrants since it requires no indicator to signal the endpoint of a titration. § Potassium permanganate solutions–even at fairly dilute concentrations–are intensely colored purple. § The product of the permanganate reduction halfreaction, manganese(II), in dilute solution shows almost no color.

Questions for discussion: 1. How can you prevent side effect from using ferrous sulfate tablets 2. Why we use the factor five with the iron- half reaction 3. Explain why: KMn. O 4 is the most commonly used oxidizing agent 4. Explain why: no external indicator is required for this titration 5. Explain why the dark purple color of KMn. O 4 solution disappears entirely during the titration 6. Explain why: Filtration in this experiment is very important 7. Explain why: When one drop excess of potassium permanganate has been added to the sample, the sample will take on a pale red/pink color?