For an experiment, 15 mL of 5% aq NaOH was added each time to the mixture for a total of 30 mL used. What is the molarity of 5% NaOH (solution density=1.055 g/mL)
To find the molarity (M) of the solution, we need to calculate the moles of NaOH and the volume of the solution.
First, let's calculate the moles of NaOH in 15 mL:
Moles of NaOH = volume (mL) × concentration (M) = 15 mL × 0.05 M = 0.75 moles
Since we added 30 mL in total, the volume of the solution is 30 mL.
Using the solution density, we can convert this volume to grams:
Mass of solution = volume (mL) × density (g/mL) = 30 mL × 1.055 g/mL ≈ 31.65 g
Now, we can calculate the molarity of the solution:
Molarity (M) = moles of solute (NaOH) / volume of solution (L)
Volume of solution = Volume of solution (mL) / 1000 = 30 mL / 1000 = 0.03 L
Molarity (M) = 0.75 moles / 0.03 L ≈ 25 M
Therefore, the molarity of the 5% NaOH solution is approximately 25 M.