Question

Express the concentration of a 0.0350 M aqueous solution of fluoride, F − , in mass percentage and in parts per million (ppm). Assume the density of the solution is 1.00 g/mL.a. Number in percentage ....%

b. Number in ppm ........ppm.

Answer 1

The concentration of the 0.0350 M aqueous solution of fluoride (F-) can be expressed as 0.0669% in mass percentage and 669 ppm in parts per million.

Step-by-step explanation:

To express the concentration of a 0.0350 M aqueous solution of fluoride (F-), we can convert it to mass percentage and parts per million (ppm).

For mass percentage, we need to calculate the mass of F- in 1 liter of solution. The molar mass of F- is 18.998 g/mol. So, the mass of F- in 1 liter of solution is:

0.0350 M x 18.998 g/mol = 0.669 g/L

To convert to mass percentage, we divide the mass of F- by the mass of the solution and multiply by 100:

Mass percentage = (0.669 g/L / 1000 g/L) x 100 = 0.0669%

For ppm, we need to convert the mass of F- in 1 liter of solution to milligrams:

0.669 g/L x 1000 mg/g = 669 mg/L

Since 1 ppm is equal to 1 mg/L, the concentration of the solution in ppm is 669 ppm.

Answer 2

(a) The mass percentage is 0.0665 %

(b) The concentration in ppm is 665 ppm.

Explanation :

Part (a) :

As we are given that, 0.0350 M aqueous solution of fluoride ion that means 0.0350 moles of fluoride ion present in 1 L of solution.

First we have to calculate the mass of fluoride ion.

`\text{Mass of }F^-=\text{Moles of }F^-* \text{Molar mass of }F^-`

Molar mass of
`F^-` = 19 g/mole

`\text{Mass of }F^-=0.0350mol* 19g/mol=0.665g`

Now we have to calculate the mass of solution.

Mass of solution = Density of solution × Volume of solution

Density of solution = 1.00 g/mL

Volume of solution = 1 L = 1000 mL

Mass of solution = 1.00 g/mL × 1000 mL

Mass of solution = 1000 g

Now we have to calculate the mass -percentage.

`\text{Mass of percentage}=\frac{\text{Mass of }F^-}{\text{Mass of solution}}* 100`

`\text{Mass of percentage}=(0.665g)/(1000g)* 100=0.0665\%`

Thus, the mass percentage is 0.0665 %

Part (b) :

Parts per million (ppm) : It is defined as the mass of a solute present in one million
`(10^6)` parts by the mass of the solution.

Now we have to calculate the concentration in ppm.

`\text{Concentration in ppm}=\frac{\text{Mass of }F^-}{\text{Mass of solution}}* 10^6`

`\text{Concentration in ppm}=(0.665g)/(1000g)* 10^6=665ppm`

Thus, the concentration in ppm is 665 ppm.