Question

How many grams of KMnO4 are needed to make 750.0 mL of a 0.175 M solution

Answer 1

How many grams of KMnO4 are needed to make 750.0 mL of a 0.175 M solution

Solution:

$$C(KMnO_4) = 0.175 \, \text{M}$$

Concentration is the amount of moles of the following substance $(KMnO_4)$ in one liter of the solution (the amount of moles can be represented as mass divided by the molar mass). It is expressed by the formula given below. The mass $m(KMnO_4)$ can be obtained from this formula as follows:

$$C(KMnO_4) = \frac{m(KMnO_4)}{M(KMnO_4)V(solution)};$$ $$m(KMnO_4) = C(KMnO_4)M(KMnO_4)V(solution) = 0.175 \, (\text{mol/l}) \times 158 \, (\text{g/mol}) \times 0.750 \, (l) = 20.74 \, \text{g}$$

Answer: $m(KMnO_4) = 20.74 \, \text{g}$