To calculate the diffusion coefficient D of a solute in a solvent, we can use the Stokes-Einstein equation:D = kT / 6r where:- D is the diffusion coefficient cm/s - k is the Boltzmann constant 1.38 10^-23 J/K - T is the temperature in Kelvin K - is the dynamic viscosity of the solvent in this case, water Pas - r is the radius of the solute molecule m First, we need to convert the temperature from Celsius to Kelvin:T = 25C + 273.15 = 298.15 KNext, we need to find the dynamic viscosity of water at 25C. According to the literature, the dynamic viscosity of water at 25C is approximately 8.9 10^-4 Pas.Now, we need to find the radius of the solute molecule. We can use the following equation to estimate the radius based on the molecular weight MW of the solute:r = 3MW / 4N ^1/3 where:- r is the radius of the solute molecule m - MW is the molecular weight of the solute g/mol - N is Avogadro's number 6.022 10^23 mol^-1 - is the density of the solute g/cm Since we don't have the density of the solute, we cannot calculate the exact radius. However, the problem states that the diffusion rate is 1.5 10^-5 cm/s. This value is already the diffusion coefficient D that we are looking for.Therefore, the diffusion coefficient of the solute in water at 25C is:D = 1.5 10^-5 cm/s