The percent by mass : 6.3%
Further explanation
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight/volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
mass of potassium nitrate = 8.4 g⇒solute
- mass of solution = mass of solute+mass of solvent(water)
mass of potassium nitrate + mass of water = 8.4 g + 125 g =133.4 g
Percent by mass of the solute :
[tex]\tt =\dfrac{mass~solute}{mass~solution}\times 100\%\\\\=\dfrac{8.4}{133.4}\times 100\%\\\\=6.3\%[/tex]
