How do you make a 0.05 M solution of iodine?

Iodine (0.05 M) 

Molecular formula: I₂ 

Molecular weight: 126.90 

Preparation: Dissolve about 14 g of iodine in a solution of 36 g of potassium iodide in  100 mL of water, add three drops of hydrochloric acid and dilute with water to 1000 mL. 

Standardization: Weigh accurately about 0.15 g of arsenic trioxide, previously dried at  105 ^oC for 1 hour, and dissolve in 20 mL of 1 M sodium hydroxide by warming, if necessary.  Dilute with 40 mL of water, add 0.1 mL of methyl orange solution and add drop-wise dilute hydrochloric acid until the yellow colour is changed to pink. 

Add 2 g of sodium carbonate dilute with 50 mL of water and add 3 mL of starch solution.  Titrate with the iodine solution until a permanent blue colour is produced. Store the solution in amber-coloured, glass stoppered bottles. 

Reaction: 

As₂O₃ + 2I₂ + 5H₂O → 2AsO³⁻₄ + 4I⁻ + 10H⁺ 

As₂O₃ + 6NaOH → 2Na₃AsO₃ + 3H₂O 

Na₃AsO₃ + I₂ + H₂O → Na₃AsO₄ + 2I⁻ + 2H⁺ 

Starch + I₂ → Starch-Iodine  (blue colour) 

Factor Calculation: 

2 moles of I₂ ≅ 1 mole of arsenic trioxide 

2000 mL of 1M I₂ ≅ 197.84 g of AS₂O₃ 

1 mL of 0.05M iodine ≅ 0.004946 g of As₂O₃

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