Question

Вещество полученное при взаимодействии 23 г натрия с 2,5 моль хлора растворили в 441,5 г воды. Вычислите массовую долю NaCl в полученном растворе.

Answer 1

2Na + Cl2 = 2NaCl

n (Na) = m/M = 23/23 = 1 моль

n (Na) < n (Cl2) => Na в недостатке => вычисления по n (Na)

n (NaCl) = n (Na) = 1 моль
m (NaCl) = n*M = 1 * 58.5 = 58.5г

W = m(в-ва) * 100 / m(р-ра)

m(р-ра) = m(NaCl) + m(H2O) = 58.5 + 441.5 = 500г

W (NaCl) = m(NaCl) * 100 / m(р-ра) = 58.5 * 100 / 500 = 11.7%

Ответ: W (NaCl) = 11.7%

Answer 2

Calculation of the Mass Fraction of NaCl in the Solution

To calculate the mass fraction of NaCl in the solution, we need to determine the amount of NaCl present in the solution and divide it by the total mass of the solution.

Given: - Mass of sodium (Na) = 23 g - Moles of chlorine (Cl) = 2.5 mol - Mass of water (H2O) = 441.5 g

To find the mass of NaCl, we need to calculate the moles of sodium (Na) and chlorine (Cl) and then use the stoichiometry of the reaction to determine the moles of NaCl formed.

The balanced chemical equation for the reaction between sodium and chlorine is:

2 Na + Cl2 → 2 NaCl

From the equation, we can see that 2 moles of sodium react with 1 mole of chlorine to form 2 moles of NaCl.

Using the given information, we can calculate the moles of sodium and chlorine:

- Moles of sodium (Na) = mass of sodium / molar mass of sodium - Moles of sodium (Na) = 23 g / 22.99 g/mol = 1 mol

- Moles of chlorine (Cl) = 2.5 mol

Since the stoichiometry of the reaction is 2:1 for sodium to chlorine, we can determine that the moles of NaCl formed will be equal to the moles of chlorine (Cl) used.

Therefore, the moles of NaCl formed = 2.5 mol.

To calculate the mass of NaCl, we can use the moles of NaCl formed and the molar mass of NaCl:

- Molar mass of NaCl = 22.99 g/mol (molar mass of Na) + 35.45 g/mol (molar mass of Cl) = 58.44 g/mol

- Mass of NaCl = moles of NaCl formed * molar mass of NaCl - Mass of NaCl = 2.5 mol * 58.44 g/mol = 146.1 g

Now, to calculate the mass fraction of NaCl in the solution, we need to divide the mass of NaCl by the total mass of the solution:

- Total mass of the solution = mass of Na + mass of Cl + mass of H2O - Total mass of the solution = 23 g + (2.5 mol * 35.45 g/mol) + 441.5 g = 23 g + 88.625 g + 441.5 g = 553.125 g

- Mass fraction of NaCl = (mass of NaCl / total mass of the solution) * 100 - Mass fraction of NaCl = (146.1 g / 553.125 g) * 100 = 26.42%

Therefore, the mass fraction of NaCl in the obtained solution is approximately 26.42%.