Calculate the molarity of a solution containing 5 g of NaOH in 450 mL solution.
Answer & explanation
Correct answer: option 2
The correct answer is option 2. 0.278 M.
To calculate the molarity of a solution, you need to know the number of moles of solute (in this case, \(NaOH)\) and the volume of the solution in liters. The formula for molarity (M) is:
\(\text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution in liters}}\)
Molar mass of \(NaOH\) \(= 23 (Na) + 16 (O) + 1 (H) = 40\, \ g/mol\)
Moles of \(NaOH \) \(= \frac{5 \text{ g}}{40 \text{ g/mol}} = 0.125 \text{ mol}\)
Volume of solution \(= 450 mL = 450/1000 = 0.450\, \ L\)
Molarity \(= \frac{0.125 \text{ mol}}{0.450 \text{ L}} = 0.278 \text{ M}\)