Answer:
1.155 moles
Explanation:
Given;
volume of solution, V = 550 mL
solution molality, M = 2.1M
Molality = number of moles of solute / litre of solvent
number of moles of solute (potassium nitrate ) = molality x litre of solvent
number of moles of solute (potassium nitrate ) = 2.1 x 550 x 10⁻³
number of moles of solute (potassium nitrate ) = 1.155 moles
Therefore, there are 1.155 moles of potassium nitrate in the solution.
