What is the percentage by mass of KCl in the solution formed by mixing 25 g of KCl in 200g of water?

Mass percentage (also known as a mass percent or weight percent) is a way to express the concentration of an element or a compound in a mixture. It is defined as the mass of the component divided by the total mass of the mixture, multiplied by 100 to get a percentage.

Mass per cent $= \frac{\mathrm{Mass} \mathrm{of} \mathrm{solute}}{ \mathrm{Total} \mathrm{mass} \mathrm{of} \mathrm{solution}} \mathrm{x} 100$

                          $= \frac{25}{200+25}\times 100$

                         = 11.11%