What weight of glucose must be dissolved in 100 g of water to lower the vapour pressure by 0.20 mm Hg? (Assume dilute solution is being formed)

Given: Vapour pressure of pure water is 54.2 mm Hg at r

Question

What weight of glucose must be dissolved in 100 g of water to lower the vapour pressure by 0.20 mm Hg? (Assume dilute solution is being formed)

Given: Vapour pressure of pure water is 54.2 mm Hg at room temperature. Molar mass of glucose is 180 g mol⁻¹

Canvas Classes · Accepted Answer

Strategy:
 According to Raoult's law for non-volatile solutes, the relative lowering of vapour pressure is equal to the mole fraction of the solute ().

Step 1: Identify given values
-  (Pure water)
- 
- Mass of water () = 100 g
- Molar mass of water = 18 g/mol
- Molar mass of glucose = 180 g/mol

Step 2: Calculate mole fraction of glucose

Step 3: Calculate moles of water ()

Step 4: Solve for mass of glucose ()
For a dilute solution:

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