Answer:
0.606 g of KNO₃.
Explanation:
We'll begin by converting 300 mL to L. This can be obtained as follow:
1000 mL = 1 L
Therefore,
300 mL = 300 mL × 1 L / 1000 mL
300 mL = 0.3 L
Next, we shall determine the number of mole of KNO₃ in the solution. This can be obtained as follow:
Volume = 0.3 L
Molarity of KNO₃ = 0.020 M
Mole of KNO₃ =?
Mole = Molarity x Volume
Mole of KNO₃ = 0.020 × 0.3
Mole of KNO₃ = 0.006 mole.
Finally, we shall determine the mass of 0.006 mole of KNO₃. This can be obtained as follow:
Mole of KNO₃ = 0.006 mole.
Molar mass of KNO₃ = 39 + 14 + (16×3)
= 39 + 14 + 48
= 101 g/mol
Mass of KNO₃ =?
Mass = mole × molar mass
Mass of KNO₃ = 0.006 × 101
Mass of KNO₃ = 0.606 g
Thus, 0.606 g of KNO₃ is needed to prepare the solution.
