A solution contains 5·85 g NaCl (Molar mass = 58·5 g mol–1) per litre of solution. It hasan osmotic pressure of 4·75 atm at 27°C. Calculate the degree of dissociation of NaCl in thissolution. (Given : R = 0·082 L atm K–1 mol–1)

To calculate the degree of dissociation (α) of NaCl in the solution, we first need to find the theoretical osmotic pressure (πt) if NaCl were completely dissociated.

1. Calculate the number of moles of NaCl in the solution:

   Number of moles = mass / molar mass Number of moles = 5.85 g / 58.5 g mol–1 = 0.1 mol

2. Calculate the molarity (M) of the solution:

   Molarity = number of moles / volume of solution Molarity = 0.1 mol / 1 L = 0.1 M

3. Calculate the theoretical osmotic pressure (πt):

   πt = MRT πt = 0.1 M * 0.082 L atm K–1 mol–1 * (273 + 27) K πt = 2.46 atm

Now, we can calculate the degree of dissociation (α) using the formula:

α = observed osmotic pressure / theoretical osmotic pressure α = 4.75 atm / 2.46 atm α = 1.93

However, the degree of dissociation cannot be greater than 1. This suggests that there is an error in the problem or the calculations. The observed osmotic pressure should not be greater than the theoretical osmotic pressure. Please check the values given in the problem.