Final answer:
The weight of the common salt thrown out can be calculated using the concept of solubility. Given that the solubility of common salt at 60 degrees Celsius is 45 and at 45 degrees Celsius is 40, the weight of the common salt thrown out is 10 grams.
Step-by-step explanation:
The weight of the common salt thrown out can be calculated using the concept of solubility.
Given that the solubility of common salt at 60 degrees Celsius is 45 and at 45 degrees Celsius is 40, we can conclude that the solubility decreases as the temperature decreases.
The initial weight of the saturated solution is 20 grams at 60 degrees Celsius. When it is cooled to 45 degrees Celsius, the solubility decreases to 40. Since the amount of solute in the solution remains constant, the excess salt that was thrown out can be calculated by subtracting the solubility at 45 degrees Celsius (40 grams) from the initial weight of the solution (20 grams). Therefore, the weight of the common salt thrown out is 20 grams - 40 grams = 10 grams.