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Molecular weight of sodium thiosulphate penta-hydrate = 248 ;
1000 ml of 3M solution contains 248 X 3 g thiosulphate ;
1 ml of 3M solution contains (248 X 3)/1000 g or 0.744 g thiosulphate.
Amount of water per ml of aqueous thiosulphate solution
= 1.25 - 0.744 = 0.506 g .
Mole fraction of thiosulphate = (mole of thiosulphate)/(total number of moles)
= (0.744/248) / {(0.744/248) + (0.506/18)}
= 0.003/(0.003 + 0.02811)
= 0.0964 .
Molarity of Sodium & thiosulphate ions:
One molecule of thiosulphate produces 2 atoms of sodium ;
One mole of thiosulphate produces 2 moles of sodium ;
1000 ml of 3M thiosulphate will produce 2 X 3 gram-atoms or 6 gram-atoms of
sodium and 3 moles of thiosulphate ions
Askiitians expert
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