From a weighed portion of a mixture of KCl and NaCl with a total mass of 0.1225 g, an AgCl

From a weighed portion of a mixture of KCl and NaCl with a total mass of 0.1225 g, an AgCl precipitate with a mass of 0.2850 g was obtained. Calculate the mass fraction of KCl and NaCl in the mixture.

Cl- + Ag + = AgCl

The mass fraction of chlorine in silver chloride will be:

w (Cl) = M (Cl) / M (AgCl) = 35.5 / 143.5 = 0.2474;

Find the mass and amount of chlorine:

m (Cl) = m (AgCl) * w (Cl) = 0.285 * 0.2474 = 0.0705 g;

n (Cl) = m (Cl) / M (Cl) = 0.002 mol;

The total amount of matter of sodium and potassium atoms will be equal to the amount of matter of chlorine atoms. The mass of sodium and potassium atoms will be:

m (Na + K) = m (NaCl + KCl) – m (Cl) = 0.1225 – 0.0705 = 0.052 g;

Let the amount of sodium substance be x mol. Since the total amount of sodium and potassium is 0.002 mol, the amount of potassium will be (0.002 – x) mol. Let’s make the equation:

x * 23 + (0.002 – x) * 39 = 0.052;

16x = 0.026;

x = 0.001625;

n (Na) = n (NaCl) = 0.001625 mol;

Find the mass and mass fraction of sodium chloride:

m (NaCl) = n (NaCl) * M (NaCl) = 0.001625 * 58.5 = 0.095 g;

w (NaCl) = m (NaCl) / m (NaCl + KCl) = 0.095 / 0.1225 = 0.776 = 77.6%;

w (KCl) = 100 – w (NaCl) = 100 – 77.6 = 22.4%.

Answer: w (NaCl) = 77.6%; w (KCl) = 22.4%.