24. Solving a chemistry problem

3. Calculate the weight of salt that needs to be taken to prepare a solution with a concentration of Sek = 0.0002 N. Reagent K3PO4, Vp-ra = 400 cm3, density = 1.0 g/cm3. Assess the possibility of hydrolysis in K3PO4 salt solution. Give the hydrolysis equation and evaluate the pH of the solution. If hydrolysis does not occur in a solution of a given salt, suggest a formula for a hydrolysable salt and justify the choice. Calculate the ionic strength of mixtures obtained by mixing solutions in equal volumes. Two solutions of K3PO4 and ZnSO4 are mixed (V=200 cm3, Cec=0.01n, density=1.0 g/cm3). Taking into account the found value of the ionic strength, calculate the values of the activity coefficients for salt ions K3PO4. Justify the choice of the equation used for the calculation. Estimate the pH of the medium formed near the electrodes as a result of the electrolysis of the K3PO4 solution.