Question

Calculate the molarity of the resulting solution prepared by diluting 25.0 mL of 18.0% ammonium chloride, NH4Cl, (density = 1.05 g/mL) to a final volume of 80.0 mL.

0.292 M 0.059 M 1.10 M 0.0536 M 0.00105 M

Answer 1

To find the molarity of the diluted NH4Cl solution, calculate the mass of NH4Cl using the density and volume, convert it to moles using molar mass, and divide by the final solution volume in liters. The resulting molarity of the solution is approximately 1.10 M.

Step-by-step explanation:

To calculate the molarity of the resulting solution after dilution, we need to follow a few steps. First, calculate the mass of NH4Cl in the original solution before dilution. Since the density of the NH4Cl solution is given as 1.05 g/mL, and we have 25.0 mL of it, we can find the mass by multiplying the volume by the density:

Mass of NH4Cl = Volume × Density = 25.0 mL × 1.05 g/mL = 26.25 g

Next, we find the mass percentage of NH4Cl to determine the grams of NH4Cl in solution:
Mass of NH4Cl in solution = Mass × Percent composition = 26.25 g × 0.18 = 4.725 g

Now, we convert the mass of NH4Cl to moles using the molar mass of NH4Cl which is approximately 53.50 g/mol:

Moles of NH4Cl = Mass of NH4Cl / Molar mass of NH4Cl = 4.725 g / 53.50 g/mol = 0.08831776 mol

Finally, we now divide the moles of NH4Cl by the final volume of the solution in liters to find the molarity. Since the final volume is 80.0 mL, which is equivalent to 0.0800 L, we have:

Molarity = Moles of NH4Cl / Volume in liters = 0.08831776 mol / 0.0800 L = 1.104 mol/L

The molarity of the resulting solution is therefore approximately 1.10 M.