Question

В воде объемом 120 мл растворили хлорид цинка массой 30 г получили раствор плот гостью 1,12 г/мл определить процентную молярную и нормальную концентрацию полученного раствора

Answer 1

1) m(H2O)=120*1=120г; W(ZnCl2)=30/150=0,2(20%).

2)m(р-ра)=1000*1,12=1120г;

150г р-ра  -   30г  (ZnCl2)

1120г р-ра -  xг  (ZnCl2)

x=224г;   n(ZnCl2)=224/136=1,65моль;  Cм=1,65моль/л.

3)Сн=1,65:2=0,825моль/л

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Answer 2

Calculation of Concentrations

To determine the percentage, molar, and normal concentrations of the solution, we need to use the given information about the volume and mass of the solute and the density of the solution.

Given: - Volume of water: 120 ml - Mass of zinc chloride: 30 g - Density of the solution: 1.12 g/ml

Percentage Concentration

The percentage concentration of a solution is the mass of the solute divided by the mass of the solution, multiplied by 100.

To calculate the percentage concentration, we need to find the mass of the solution. The mass of the solution is the sum of the mass of the solute (zinc chloride) and the mass of the water.

Mass of the solution = Mass of zinc chloride + Mass of water

Mass of the solution = 30 g + (120 ml * 1.12 g/ml)

Now we can calculate the percentage concentration:

Percentage concentration = (Mass of zinc chloride / Mass of the solution) * 100

Let's calculate it step by step:

1. Calculate the mass of the solution: - Mass of the solution = 30 g + (120 ml * 1.12 g/ml) - Mass of the solution = 30 g + 134.4 g - Mass of the solution = 164.4 g

2. Calculate the percentage concentration: - Percentage concentration = (30 g / 164.4 g) * 100 - Percentage concentration ≈ 18.25%

Therefore, the percentage concentration of the solution is approximately 18.25%.

Molar Concentration

The molar concentration of a solution is the number of moles of the solute divided by the volume of the solution in liters.

To calculate the molar concentration, we need to find the number of moles of zinc chloride. The number of moles can be calculated using the formula:

Number of moles = Mass of zinc chloride / Molar mass of zinc chloride

The molar mass of zinc chloride (ZnCl2) is calculated by adding the atomic masses of zinc (Zn) and chlorine (Cl).

Molar mass of ZnCl2 = (Atomic mass of Zn) + 2 * (Atomic mass of Cl)

Now we can calculate the molar concentration:

Molar concentration = Number of moles / Volume of solution (in liters)

Let's calculate it step by step:

1. Calculate the molar mass of zinc chloride: - Atomic mass of Zn = 65.38 g/mol - Atomic mass of Cl = 35.45 g/mol - Molar mass of ZnCl2 = 65.38 g/mol + 2 * 35.45 g/mol - Molar mass of ZnCl2 ≈ 136.28 g/mol

2. Calculate the number of moles of zinc chloride: - Number of moles = 30 g / 136.28 g/mol - Number of moles ≈ 0.220 mol

3. Convert the volume of the solution to liters: - Volume of solution = 120 ml = 120 ml / 1000 ml/L - Volume of solution = 0.120 L

4. Calculate the molar concentration: - Molar concentration = 0.220 mol / 0.120 L - Molar concentration ≈ 1.833 mol/L

Therefore, the molar concentration of the solution is approximately 1.833 mol/L.

Normal Concentration

The normal concentration of a solution is the number of gram-equivalents of the solute divided by the volume of the solution in liters.

To calculate the normal concentration, we need to find the number of gram-equivalents of zinc chloride. The number of gram-equivalents can be calculated using the formula:

Number of gram-equivalents = Mass of zinc chloride / Equivalent mass of zinc chloride

The equivalent mass of zinc chloride (ZnCl2) is calculated by dividing the molar mass by the number of equivalents.

Equivalent mass of ZnCl2 = Molar mass of ZnCl2 / Number of equivalents

Now we can calculate the normal concentration:

Normal concentration = Number of gram-equivalents / Volume of solution (in liters)

Let's calculate it step by step:

1. Calculate the equivalent mass of zinc chloride: - Number of equivalents = 2 (since zinc chloride has 2 chloride ions) - Equivalent mass of ZnCl2 = 136.28 g/mol / 2 - Equivalent mass of ZnCl2 ≈ 68.14 g/equiv

2. Calculate the number of gram-equivalents of zinc chloride: - Number of gram-equivalents = 30 g / 68.14 g/equiv - Number of gram-equivalents ≈ 0.440 equiv

3. Calculate the normal concentration: - Normal concentration = 0.440 equiv / 0.120 L - Normal concentration ≈ 3.667 equiv/L

Therefore, the normal concentration of the solution is approximately 3.667 equiv/L.

Summary

- Percentage concentration: approximately 18.25% - Molar concentration: approximately 1.833 mol/L - Normal concentration: approximately 3.667 equiv/L

Please note that these values are approximate due to rounding during calculations.