Express the concentration of a 0.0860 M aqueous solution of fluoride, F–, in mass percentage and in parts per million. Assume the density of the solution is 1.00 g/mL.
0.0860M F^- = 0.0860 mols/L soln.
How many g is 0.0860 mols F^-? That is 0.0860 x atomic mass F = approximately 1.6 g but you need to do it more accurately.
If the L of solution has a mass of 1000 g, then the %by mass = (mass F^-/mass soln)*100 = ?
Then convert to mg/L to find ppm.
To express the concentration of a solution in mass percentage and parts per million (ppm), we need to calculate the mass of the solute (fluoride, F–) and then determine the ratio of that mass to the mass of the solution.
Given:
- Concentration of the fluoride solution (C) = 0.0860 M
- Density of the solution (ρ) = 1.00 g/mL
To calculate the mass of fluoride in the solution, we need to know the molar mass of fluoride (F–). The molar mass of fluoride is 19.00 g/mol.
To calculate the mass of fluoride (mF) in the solution, we can use the formula:
mF = C × V × MF
Where:
- C is the concentration of the solution in mol/L
- V is the volume of the solution in L
- MF is the molar mass of fluoride in g/mol
Since the volume is not provided, we can assume it to be 1.00 L as the density of the solution is given as 1.00 g/mL. Therefore, 1.00 L solution will have a mass of 1.00 kg or 1000 g.
mF = 0.0860 mol/L × 1.00 L × 19.00 g/mol = 1.634 g
Now, we can calculate the mass percentage:
Mass Percentage (w/w %) = (mass of solute / mass of solution) × 100
Here, the mass of the solute (fluoride) is 1.634 g, and the mass of the solution is 1000 g.
Mass Percentage (w/w %) = (1.634 g / 1000 g) × 100 = 0.1634%
To calculate the concentration in parts per million (ppm), we can use the following formula:
ppm = (mass of solute / mass of solution) × 10^6
ppm = (1.634 g / 1000 g) × 10^6 = 1634 ppm
Therefore, the concentration of the 0.0860 M aqueous solution of fluoride is approximately 0.1634% (w/w) and 1634 ppm.