Final answer:
To calculate the percentage of KCl in a mixture, subtract the mass of NaCl from the total mass of the mixture and then divide the mass of KCl by the total mass, multiplying by 100 to get the percentage. In this case, it is 64.936%.
Step-by-step explanation:
To find the percentage of KCl in the mixture, we must subtract the mass of NaCl from the total mass of the mixture. The given sample weighs 15.3882 g, and it contains 5.3961 g of NaCl. To determine the mass of KCl, we subtract the mass of NaCl from the total mass of the mixture: 15.3882 g - 5.3961 g = 9.9921 g of KCl.
Next, to find the percentage of KCl in the mixture, we use the formula:
Percentage (%) = (mass of KCl / total mass of mixture) x 100
Inserting the values, we get:
Percentage of KCl = (9.9921 g / 15.3882 g) x 100 = 64.936% (rounded to three decimal places).