Prepare 0.1 molar HCl in 100ml of volumetric flask from stock solution of 37%. ( density = 1.19g/cm3. Show all necessary steps

Answer 1

To prepare a 0.1 M HCl solution from a stock solution of 37% HCl, you will first need to calculate the molarity of the stock solution. Then, you can use the dilution equation to find the volume of the stock solution required to achieve the desired concentration. Here's a step-by-step procedure:

Step 1: Calculate the Molarity of the Stock Solution

1. Determine the density of the stock solution:

   • Density = 1.19 g/cm³ = 1.19 g/mL

2. Calculate the mass of HCl in 1 liter of the stock solution:

   • A 37% (w/w) solution means there are 37 grams of HCl in 100 grams of solution.

   \[ \text{Mass of solution} = 1000 \text{ mL} \times 1.19 \text{ g/mL} = 1190 \text{ g} \]

   So, the mass of HCl in 1190 g of the solution:

   \[ \text{Mass of HCl} = \frac{37}{100} \times 1190 \text{ g} = 434.3 \text{ g} \]

3. Calculate the number of moles of HCl:

   • The molar mass of HCl is approximately 36.46 g/mol.

   \[ \text{Moles of HCl} = \frac{434.3 \text{ g}}{36.46 \text{ g/mol}} \approx 11.92 \text{ mol} \]

4. Calculate the molarity of the stock solution: \[ \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution in liters}} = \frac{11.92 \text{ mol}}{1 \text{ L}} = 11.92 \text{ M} \]

Step 2: Use the Dilution Equation

To dilute the stock solution to the desired concentration:

\[ C_1V_1 = C_2V_2 \]

Where:

• \( C_1 \) = concentration of stock solution (11.92 M)
• \( V_1 \) = volume of stock solution needed (unknown)
• \( C_2 \) = concentration of diluted solution (0.1 M)
• \( V_2 \) = volume of diluted solution (100 mL = 0.1 L)

Rearranging for \( V_1 \):

\[ V_1 = \frac{C_2V_2}{C_1} = \frac{0.1 \text{ M} \times 0.1 \text{ L}}{11.92 \text{ M}} \approx 0.000839 \text{ L} = 0.839 \text{ mL} \]

Step 3: Prepare the Dilution

1. Measure 0.839 mL of the 37% stock solution using a pipette.
2. Transfer the measured stock solution into a 100 mL volumetric flask.
3. Add distilled water to the volumetric flask until the total volume reaches 100 mL. Make sure to mix well to ensure uniform distribution of the HCl in the solution.

Step 4: Label the Solution

Label the flask with the concentration (0.1 M HCl) and the date prepared.

Summary

You have now successfully prepared a 0.1 M HCl solution from a 37% stock solution with a density of 1.19 g/cm³.