The mass of a non-volatile solute of molar mass 40 ~g ~mol ~m ⁻¹ that should be dissolved in 114 ~g of octane to lower its vapour pressure by 20 % is

Step-by-step solution

p ⁰=100, p =100-20=80 m =40 M ( C ₈ H ₁₈ )=114 w =? ~W =114 p ^ - p p = w m M W 100-80 80 = w 40 114 114 or 20 80 = w 40 or w = 20 40 80 =10 ~g