* 2.18 Calculate the mass of a non-volatile solute (molar mass 40 g mo

1.	* 2.18 Calculate the mass of a non-volatile solute (molar mass 40 g mol") whichshould be dissolved in 114 g octane to reduce its vapour pressure to 80%.
Answer» EXPLANATION: Let p be the vapour pressure of pure OCTANE. The vapour pressure of solution will be 80/100p=0.8p Molar MASS of solute (M) and octane (m) are 40 g/mol and 114 g/mol respectively. Mass of octane, w is 114 g. p−p'/p=Wm/Me p-0.8p/p=W114/40114 W=8gm Hence, 8 g of solute are required

* 2.18 Calculate the mass of a non-volatile solute (molar mass 40 g mol") whichshould be dissolved in 114 g octane to reduce its vapour pressure to 80%.

Answer»

Let p be the vapour pressure of pure OCTANE. The vapour pressure of solution will be

80/100p=0.8p

Molar MASS of solute (M) and octane (m) are 40 g/mol and 114 g/mol respectively. Mass of octane, w is 114 g.

p−p'/p=Wm/Me

p-0.8p/p=W*114/40*114

W=8gm

Hence, 8 g of solute are required