Compare the osmotic pressure of Solution A contains 7 g/L of `MgCl_(2)` and solution B contains 7 g/L of NaCl at room temperature.

Options

A. Solution A is greater than B.
B. Both have same osmotic pressure
C. Solution B is greater than A.
D. Cannot be determined

Answer

C

Explanation

Osmotic pressure is a colligative property. More the number of particles (or ions) in solution, more will be osmotic pressure.
NaCl solution (Solution B)
Given, mass of NaCl = 7s, V = 1 L
`:.` Concentration
` = ("mass")/( "mol. Mass " ) = (7)/(58.5) = 0.119 ` M
NaCl dissociates as follows
`NaCI rarr Na^(+) CI_(-)` (2 ions )
`:.` oncentration of ions in solution
`= 2xx 0.119 M`
`= 0.238 ` M
MgCl solution (Solution A)
Given, mass of `MgCl_(2) ` = 7g, V = 1L
`:. `Concentration
`= ("mass")/("mol. mass") = (7)/(95) = 0.0747 `
`MgCl_(2)` dissociates as follows:
`MgCI_(2) rarr Mg^(2) + 2CI^(-) ` (3 ions )
`:.` Concentration of ions in solution
`3 xx 0.074 M`
`= 0.0222` M
`because ` umber of particles in solution B (NaCl) are more than in solution A.
`because ` smotic pressure of solution B (NaCl) will be more than solution A.