Chemistry · Colligative properties of dilute solutions: a relative lowering of vapour pressure, depression of freezing point, the elevation of boiling point and osmotic pressure

18 g glucose \) is added to of water. The vapour pressure of this aqueous soluti

18 g glucose \( \left(C_{6} H_{12} O_{6}\right) \) is added to \( 178.2 \mathrm{g} \) of water. The vapour pressure of this aqueous solution at \( 100^{0} C \) in torr is:

  • A. 7.60
  • B. 76.00
  • C. 752.40
  • D. 759.00

Step-by-step solution

Calculate moles of glucose (18 g / 180 g/mol = 0.1 mol) and water (178.2 g / 18 g/mol = 9.9 mol). Mole fraction of water = 9.9 / (9.9+0.1) = 0.99. At 100°C, pure water vapour pressure = 760 torr. Raoult's law: P_solution = 0.99 × 760 = 752.4 torr.
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