How do you make 0.1 M sodium thiosulphate solution?

Sodium Thiosulphate (0.1M) 

Molecular formula: Na₂S₂O₃ 

Molecular weight: 158.11 

Preparation: Dissolve 25 g of sodium thiosulphate and 0.2 g of sodium carbonate in carbon dioxide-free water and dilute to 1000 mL with the same solvent. 

Standardization: Dissolve 0.2 g of potassium bromate, weighed accurately, in sufficient water to produce 250 mL. To 50.0 mL of this solution add 2 g of potassium iodide and 3 mL of 2 M hydrochloric acid and titrate with the sodium thiosulphate solution using the starch solution, added towards the end of the titration, as an indicator until the blue color is discharged [I₂ forms a blue colored complex with starch]. Re-standardize the solution frequently. 

Reaction: 

KBrO₃ + HI → HIO₃ + KBr 

IO⁻₃ + 5I⁻ + 6H⁺ → 3I₂ + 3H₂O 

3[2Na₂S₂O₃ + I₂ → Na₂S₄O₆ + 2NaI] 

Factor Calculation: 

Since,

6Na₂S₂O₃ ≅ 3I2 ≅ HIO₃ ≅ KBrO₃ 

6 moles of Na₂S₂O₃ ≅ 1 mole of KBrO₃ 

6000 mL of 1M Na₂S₂O₃ ≅ 167 g of KBrO₃ 

1 mL of 0.1M Na₂S₂O₃ ≅ 0.002783 g of KBrO₃

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