2 A chemical procedure requires 500 g of a 125 wt AgNO3 aque

2. A chemical procedure requires 500 g of a 12.5 wt-% AgNO3 aqueous solution. a. Determine the mass of pure solid AgNO; required b. This solution is to be prepared from impure solid AgNO,. The label on the jar of silver nitrate indicates the material available has a purity of 8 Compute the weight of impure solid silver nitrate and the weight of water which must be used to dissolve the impure solid to prepare the desired solution. 4.2 wt-%.

Solution

Ans. Given, [AgNO₃] = 12.5 % (w/w)

            Required amount of solution = 500.0 g

#a. A 12.5 % (w/w) means that there is 12.5 g solute per 100.0 g solution.

Required mass of pure AgNO₃ = w/w % [AgNO₃] x Mass of solution

                                                = (12.5 g AgNO3 / 100 g solution) x 500 g solution

                                                = 62.5 g AgNO₃

Therefore, required mass of AgNO₃ = 62.5 g

#b. Let the required mass of impure sample = X

So,

            84.2 % of X = 62.5 g

            Or, X = 62.5 g / 0.842

            Hence, X = 74.228 g

Therefore, required mass of impure sample = 74.23 g

# Required mass of water (solvent) = Total mass of solution – Mass of solute

                                                = 500.0 g – 74.23 g

                                                = 425.77 g