A certain amount of NaOH is dissolved in 98.0 g of water at 25 °C. The final volume of NaOH solution is 100 mL. Given the density of the solution is 1.33 g/mL at 25 °C, calculate the number of moles of NaOH used.
Answer (1)
To calculate the number of moles of NaOH used in the solution, we need to follow these steps:
Calculate the Mass of the Solution: The final volume of the solution is given as 100 mL, and the density of the solution is 1.33 g/mL. Using the formula for density Density = Volume Mass , we can find the mass of the solution:
Mass of solution = Density × Volume = 1.33 g/mL × 100 mL = 133 g
Determine the Mass of NaOH: Since the mass of the water alone is 98.0 g, the mass of NaOH in the solution is:
Mass of NaOH = Mass of solution − Mass of water = 133 g − 98.0 g = 35.0 g
Calculate the Moles of NaOH: The molar mass of NaOH is approximately 40.00 g/mol. We can now calculate the number of moles of NaOH using the formula:
Moles of NaOH = Molar mass of NaOH Mass of NaOH = 40.00 g/mol 35.0 g = 0.875 moles
Therefore, the number of moles of NaOH used in the solution is 0.875 moles.
