Express the concentration of a 0.0700 M aqueous solution of fluoride, F-, in mass percentage and in part per million. Assume the density of the solution is 1.00 g/mL.
0.07M is 0.07 mols/L solution
mols = g/atomic mass
0.07 = g/19 so g F^- = approx 1.33 g/L solution or 0.133 g/100 mL solution = 0.133 g/100 g solution.
mass% = g F^-/100 g solution.
ppm = mass% x (1E6/1E2) = 1E4 x mass%
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To express the concentration of a solution in mass percentage and in parts per million (ppm), you'll need to follow a few steps:
Step 1: Calculate the mass of fluoride (F-) in the given volume of solution.
To calculate the mass of fluoride, you'll need to know the density of the solution and the volume of the solution.
Given:
Concentration of the solution (C) = 0.0700 M
Density of the solution = 1.00 g/mL
Volume of the solution = Not provided
We can assume that the volume of the solution is 1.00 L (since the concentration is given in Molarity). However, it's always a good practice to confirm the volume if explicitly provided.
Using the formula C = moles/volume, we can calculate the number of moles of fluoride (F-) in the solution:
moles = C × volume
moles = 0.0700 mol/L × 1.00 L = 0.0700 mol
Step 2: Calculate the mass of fluoride using its molar mass.
The molar mass of fluoride (F-) is 18.998 g/mol.
mass = moles × molar mass
mass = 0.0700 mol × 18.998 g/mol = 1.33 g
So, the mass of fluoride in the solution is 1.33 grams.
Step 3: Calculate the mass percentage.
Mass percentage = (mass of fluoride / mass of solution) × 100
The mass of the solution is equal to its density (1.00 g/mL) since the volume assumed was 1.00 L.
Mass percentage = (1.33 g / 1.00 g) × 100 = 133%
The mass percentage is 133%.
Step 4: Calculate parts per million (ppm).
ppm = (mass of fluoride / mass of solution) × 10^6
ppm = (1.33 g / 1.00 g) × 10^6 = 1.33 × 10^6 ppm
The concentration of the 0.0700 M aqueous solution of fluoride (F-) in mass percentage is 133%, and in parts per million (ppm) is 1.33 × 10^6 ppm.