Determine the concentrations of MgCl2 Mg2+ and Cl- in a solution prepared by dissolving 2.73*10^-4g MgCl2 in 1.00L of water. Express all the concentrations in molarity. Additionally, express the concentrations of the ionic species in ppm.
MgCl2= ____ M
Mg2+ = ____ M = _____ ppm
Cl- = ____ M = _____ ppm
mols MgCl2 = grams/molar mass = ? and that in 1.00 L solution is that Molarity.
So MgCl2 is ? M
Mg^2+ is ? M; i.e., the same as MgCl2 since there is 1 Mg^2+/MgCl2.
Cl^- is 2? Mi.e., twice Mg^2+ since there are 2 Cl^- per MgCl2.
To convert to ppm, Convert grams in the problem to mg MgCl2 and remember the definition that 1 ppm = 1 mg/L solution.
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 water.
1. Calculate the molar mass of MgCl2:
MgCl2: Mg - 24.31 g/mol, Cl - 35.45 g/mol
Molar mass of MgCl2 = (24.31 g/mol) + 2(35.45 g/mol) = 95.21 g/mol
2. Calculate the number of moles of MgCl2:
moles of MgCl2 = mass of MgCl2 / molar mass of MgCl2
moles of MgCl2 = 2.73 × 10^-4 g / 95.21 g/mol = 2.86 x 10^-6 mol
3. Calculate the concentration of MgCl2:
concentration (M) = moles / volume (L)
concentration of MgCl2 = 2.86 × 10^-6 mol / 1.00 L = 2.86 × 10^-6 M
So, the concentration of MgCl2 in the solution is 2.86 × 10^-6 M.
To determine the concentrations of Mg2+ and Cl- ions, we need to consider the dissociation of MgCl2 into its ions. Each formula unit of MgCl2 produces one Mg2+ ion and two Cl- ions.
4. Calculate the concentration of Mg2+:
Since the concentration of MgCl2 and Mg2+ ions are the same, the concentration of Mg2+ is also 2.86 × 10^-6 M.
5. Calculate the concentration of Cl-:
The concentration of Cl- is molar concentration of MgCl2 multiplied by the number of Cl- ions produced per formula unit of MgCl2:
concentration of Cl- = (2 x concentration of MgCl2) = 2 × 2.86 × 10^-6 M = 5.72 × 10^-6 M
To convert the concentrations of Mg2+ and Cl- ions into ppm, we need to use the conversion factor:
6. Calculate the concentration of Mg2+ in ppm:
concentration (ppm) = concentration (M) * molar mass (g/mol) * 1000
concentration of Mg2+ (ppm) = 2.86 × 10^-6 M * 24.31 g/mol * 1000 = 69.6 ppm
7. Calculate the concentration of Cl- in ppm:
concentration of Cl- (ppm) = 5.72 × 10^-6 M * 35.45 g/mol * 1000 = 202 ppm
So, the concentrations are:
MgCl2: 2.86 × 10^-6 M
Mg2+: 2.86 × 10^-6 M (69.6 ppm)
Cl-: 5.72 × 10^-6 M (202 ppm)