Potassium nitrate weighing 15 g was dissolved in water volume of 200 cm3. Calculate the mass fraction of KNO3 in solution.
To calculate the mass fraction of KNO3 in the solution, you need to know the masses of both the KNO3 and the entire solution.
In this case, you know that the mass of KNO3 is 15 g. However, to find the mass of the entire solution, you need to consider the density of water and the volume of the solution.
The density of water is 1 g/cm3. So, you can calculate the mass of the entire solution using the formula:
Mass = density x volume
Mass of the entire solution = 1 g/cm3 x 200 cm3 = 200 g
Now that you have the mass of both the KNO3 (15 g) and the entire solution (200 g), you can calculate the mass fraction of KNO3.
Mass fraction of KNO3 = (mass of KNO3) / (mass of entire solution) x 100%
Mass fraction of KNO3 = (15 g) / (200 g) x 100% = 7.5%
Therefore, the mass fraction of KNO3 in the solution is 7.5%.