The molar mass of NaOH is $40.00 g / mol$. If 5.20 g NaOH are dissolved in 0.500 L of solution, what is the molarity of the solution?
Use molarity $=\frac{\text { moles of solute }}{\text { liters of solution }}$.
A. 0.0125 M
B. 0.260 M
C. 3.85 M
D. 7.69 M
Answer (1)
0.26 M
Explanation
Problem Analysis We are given the mass of NaOH (5.20 g), the molar mass of NaOH (40.00 g/mol), and the volume of the solution (0.500 L). We need to find the molarity of the solution using the formula: Molarity = liters of solution moles of solute .
Calculating Moles of NaOH First, we need to calculate the number of moles of NaOH. We can use the formula: Moles = molar mass mass . Substituting the given values, we get: Moles of NaOH = 40.00 g/mol 5.20 g = 0.13 mol .
Calculating Molarity Now, we can calculate the molarity of the solution using the formula: Molarity = liters of solution moles of solute . Substituting the calculated moles of NaOH and the given volume of the solution, we get: Molarity = 0.500 L 0.13 mol = 0.26 M .
Final Answer Therefore, the molarity of the NaOH solution is 0.26 M.
Examples
Molarity calculations are essential in various fields, including chemistry, biology, and medicine. For instance, when preparing a saline solution for intravenous administration, accurately calculating the molarity ensures the correct concentration of salt is administered to the patient, preventing complications. Similarly, in chemical experiments, precise molarity is crucial for controlling reaction rates and yields. Understanding molarity helps in accurately preparing solutions for household cleaning, gardening, and cooking, ensuring the desired effect without causing harm.
