Question

к раствору 650 мл с массовой долей гидроксида натрия 40% и плотностью 1,44 г/мл прилили 250 мл воды. Определите массовую долю гидроксида натрия в полученном растворе?

Answer 1

Calculation of the Mass Fraction of Sodium Hydroxide in the Solution

To determine the mass fraction of sodium hydroxide (NaOH) in the solution, we need to consider the initial solution and the added water.

Given information: - Initial solution volume: 650 mL - Mass fraction of sodium hydroxide in the initial solution: 40% - Density of the initial solution: 1.44 g/mL - Volume of water added: 250 mL

To calculate the mass fraction of sodium hydroxide in the final solution, we can follow these steps:

1. Calculate the mass of the initial solution: - Mass = Volume × Density - Mass = 650 mL × 1.44 g/mL

2. Calculate the mass of sodium hydroxide in the initial solution: - Mass of NaOH = Mass of the initial solution × Mass fraction of NaOH - Mass of NaOH = (650 mL × 1.44 g/mL) × 40%

3. Calculate the mass of water added: - Mass of water = Volume of water added × Density of water - Mass of water = 250 mL × 1 g/mL (since the density of water is approximately 1 g/mL)

4. Calculate the total mass of the final solution: - Total mass = Mass of the initial solution + Mass of water added

5. Calculate the mass fraction of sodium hydroxide in the final solution: - Mass fraction of NaOH = (Mass of NaOH / Total mass) × 100%

Let's perform the calculations:

1. Calculate the mass of the initial solution: - Mass = 650 mL × 1.44 g/mL = 936 g

2. Calculate the mass of sodium hydroxide in the initial solution: - Mass of NaOH = (936 g) × (40/100) = 374.4 g

3. Calculate the mass of water added: - Mass of water = 250 mL × 1 g/mL = 250 g

4. Calculate the total mass of the final solution: - Total mass = 936 g + 250 g = 1186 g

5. Calculate the mass fraction of sodium hydroxide in the final solution: - Mass fraction of NaOH = (374.4 g / 1186 g) × 100% ≈ 31.55%

Therefore, the mass fraction of sodium hydroxide in the final solution is approximately 31.55%.

Please note that the calculations are based on the given information and assumptions about the density of water.