What weight of dextrose, C6H12O6, dissolved in 2000 grams of water, will raise the boiling-point to 102.04C at one atmosphere pressure?
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ΔT = (Kb) m
where
ΔT = change in boiling point of the solvent
Kb = molal boiling point elevation constant = 0.512 °C / m
m = molality = moles of solute / kg of solvent
Let's first calculate the molality:
m = moles of solute / kg of solvent
m = (mass of solute / molecular weight of solute) / kg of solvent
m = (x grams of dextrose / 180.16 g/mol) / 2 kg of water
ΔT = (Kb) m
2.04 = (0.512) [(x / 180.16) / 2]
2.04 = (0.256) (x / 180.16)
x = (2.04)(180.16) / (0.256)
x = 1435.65 grams of dextrose
Hope this helps...good luck!
where
ΔT = change in boiling point of the solvent
Kb = molal boiling point elevation constant = 0.512 °C / m
m = molality = moles of solute / kg of solvent
Let's first calculate the molality:
m = moles of solute / kg of solvent
m = (mass of solute / molecular weight of solute) / kg of solvent
m = (x grams of dextrose / 180.16 g/mol) / 2 kg of water
ΔT = (Kb) m
2.04 = (0.512) [(x / 180.16) / 2]
2.04 = (0.256) (x / 180.16)
x = (2.04)(180.16) / (0.256)
x = 1435.65 grams of dextrose
Hope this helps...good luck!