Question

6.7 mL of a potassium chloride solution was added to a 54.730 g evaporating dish. The combination weighed 61.945 g. After evaporation the dish and contents weighed 55.428 g.

a. What was the mass percent of potassium chloride in the solution?

Answer 1

The mass percent of potassium chloride in the solution is calculated by finding the mass of KCl left after evaporation and dividing that by the initial mass of the solution, then multiplying by 100 to get the percentage.

Step-by-step explanation:

The question is asking to calculate the mass percent of potassium chloride (KCl) in the solution given the initial and final weights of the evaporating dish and its contents. To find the mass of KCl, subtract the final weight after evaporation (55.428 g) from the initial weight of the dish plus the solution (61.945 g), which gives us the mass of the KCl left after water has evaporated. The mass of KCl is then divided by the total initial mass of the solution (6.7 mL of KCl solution) and multiplied by 100 to get the mass percent of KCl in the solution.

Mass of KCl = Final weight after evaporation - Weight of the empty dish
Mass of KCl = 55.428 g - 54.730 g = 0.698 g

Mass percent of KCl = (Mass of KCl / Initial mass of solution) x 100
Mass percent of KCl = (0.698 g / 6.7 mL) x 100 = 10.42%