What is the molar concentration of a solution prepared by dissolving 25.75 g of NaOH in water to produce 500.0 mL of solution?

• A. 49.50 M
• B. 1.288 M
• C. 0.6438 M
• D. 0.001288 M
• E. 0.05550 M

Answer: (B)

Verified step by step guidance

1. First, calculate the molar mass of NaOH. The molar mass is the sum of the atomic masses of sodium (Na), oxygen (O), and hydrogen (H). Use the periodic table to find these values: Na = 22.99 g/mol, O = 16.00 g/mol, H = 1.01 g/mol. Add them together to get the molar mass of NaOH.
2. Next, convert the mass of NaOH from grams to moles using the formula: \( \text{moles of NaOH} = \frac{\text{mass of NaOH (g)}}{\text{molar mass of NaOH (g/mol)}} \). Substitute the given mass of NaOH (25.75 g) and the molar mass calculated in the previous step.
3. Now, convert the volume of the solution from milliliters to liters, since molar concentration is expressed in moles per liter. Use the conversion: \( 1 \text{ L} = 1000 \text{ mL} \). Therefore, \( 500.0 \text{ mL} = 0.5000 \text{ L} \).
4. Calculate the molar concentration (M) of the solution using the formula: \( M = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \). Substitute the moles of NaOH and the volume of the solution in liters.
5. Finally, compare the calculated molar concentration with the given options to determine the correct answer.