How to prepare 100 ml of 0.025n sodium thiosulfate?
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Sodium thiosulfate usually exist as Na2S2O3·5H2O
with a molar mass of 248g/mol
This mass contains 158g of sodium thiosulfate
100ml of 0.025M Sodium thiosulfate will contain = 100/1000 x 0.025 = 0.0025 moles of the thiosulfate.
This has a mass of = 0.0025 x 158 = 0.395 ≈ 0.4g of sodium thiosulfate
if 158g is contained in 248g of hydrated salt
∴ 0.4g = ( 0.4 x 248)/158 = 0.6g
PREPARATION
1. Measure 0.6g of hydrated sodium thiosulfate using electric balance and add it in to a 100ml volumetric flask
2. Add some distilled water, about 30ml or so
3. Shake well for the sodium thiosulfate to dissolve
4. Add more water and shake
5. Finally, let the flask stand and add water little at a time carefully until it reaches the 100ml mark
This will be a 0.025M sodium thiosulfate solution
with a molar mass of 248g/mol
This mass contains 158g of sodium thiosulfate
100ml of 0.025M Sodium thiosulfate will contain = 100/1000 x 0.025 = 0.0025 moles of the thiosulfate.
This has a mass of = 0.0025 x 158 = 0.395 ≈ 0.4g of sodium thiosulfate
if 158g is contained in 248g of hydrated salt
∴ 0.4g = ( 0.4 x 248)/158 = 0.6g
PREPARATION
1. Measure 0.6g of hydrated sodium thiosulfate using electric balance and add it in to a 100ml volumetric flask
2. Add some distilled water, about 30ml or so
3. Shake well for the sodium thiosulfate to dissolve
4. Add more water and shake
5. Finally, let the flask stand and add water little at a time carefully until it reaches the 100ml mark
This will be a 0.025M sodium thiosulfate solution
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