To determine the concentrations of MgCl2, Mg2+, and Cl- in the solution, we first need to calculate the number of moles of MgCl2 dissolved in the water.
Step 1: Convert the mass of MgCl2 to moles.
Given: Mass of MgCl2 = 2.39 x 10^-4 g.
The molar mass of MgCl2 can be calculated from the periodic table:
Mg = 24.31 g/mol
Cl = 35.45 g/mol (x2) = 70.9 g/mol
MgCl2 = 24.31 + 70.9 = 95.21 g/mol
To convert the mass to moles, we'll use the formula:
moles = mass / molar mass
moles of MgCl2 = 2.39 x 10^-4 g / 95.21 g/mol
Step 2: Calculate the concentration of MgCl2 in molarity.
Molarity (M) is defined as moles of solute divided by volume of solution in liters (L):
Molarity (M) = moles / volume
Given: Volume = 2.50 L
Concentration of MgCl2 in molarity = moles of MgCl2 / volume
Step 3: Calculate the concentration of Mg2+ and Cl-.
In 1 mole of MgCl2, there is 1 mole of Mg2+ ions and 2 moles of Cl- ions.
Concentration of Mg2+ in molarity = concentration of MgCl2 in molarity
Concentration of Cl- in molarity = 2 x concentration of MgCl2 in molarity
Step 4: Calculate the concentrations in parts per million (ppm).
To convert the concentration from molarity to ppm, use the conversion factor:
1 ppm = 1 mg/L = 1 mg/kg = 1 mg/g = 1 g/10^6 g
Concentration in ppm = concentration in molarity x molar mass (g/mol) x 10^6
Now you have the step-by-step procedure to determine the concentrations of MgCl2, Mg2+, and Cl-. You can substitute the given values into the equations to find the answers.