what is the concentration (M) of a MgCl2 solution prepared by dissolving 7.2 g of MgCl2 in sufficient water to give 362 mL of solution?
To calculate the concentration (Molarity, M) of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).
Step 1: Convert the mass of MgCl2 to moles.
The molar mass of MgCl2 is 95.211 g/mol. Divide the given mass (7.2 g) by the molar mass to find the number of moles of MgCl2.
7.2 g / 95.211 g/mol = 0.0756 mol
Step 2: Convert the volume of the solution to liters.
The given volume is 362 mL. Divide by 1000 to convert it to liters.
362 mL / 1000 = 0.362 L
Step 3: Calculate the concentration (Molarity).
Use the formula: Molarity (M) = moles (mol) / volume (L)
Molarity = 0.0756 mol / 0.362 L = 0.209 M
Therefore, the concentration of the MgCl2 solution is approximately 0.209 M.
To find the concentration (M) of the MgCl2 solution, we need to know the number of moles of MgCl2 and the volume of the solution.
1. Start by calculating the number of moles of MgCl2:
The molar mass of MgCl2 is the sum of the atomic masses of magnesium (Mg) and chlorine (Cl).
Mg: 24.31 g/mol
Cl: 35.45 g/mol
Molar mass of MgCl2 = (1 × Mg) + (2 × Cl) = (1 × 24.31 g/mol) + (2 × 35.45 g/mol) = 95.21 g/mol
To find the number of moles, divide the mass of MgCl2 by its molar mass:
Number of moles = mass / molar mass = 7.2 g / 95.21 g/mol ≈ 0.076 moles
2. Next, calculate the volume of the solution in liters:
The given volume is 362 mL. To convert it to liters, divide by 1000:
Volume of solution = 362 mL / 1000 mL/L = 0.362 L
3. Finally, calculate the concentration (M) using the formula:
Concentration (M) = moles / volume (in liters)
Concentration (M) = 0.076 moles / 0.362 L ≈ 0.210 M
Therefore, the concentration (M) of the MgCl2 solution is approximately 0.210 M.