We’re being asked to determine the mass percent of HF in a stock solution of 15 M hydrofluoric acid (HF) solution.

**Mass** or **weight percent (% by mass)**is the percentage of a given element or compound within a solution. The equation used to calculate for mass percent is shown below:

$\overline{){\mathbf{m}}{\mathbf{a}}{\mathbf{s}}{\mathbf{s}}{\mathbf{}}{\mathbf{p}}{\mathbf{e}}{\mathbf{r}}{\mathbf{c}}{\mathbf{e}}{\mathbf{n}}{\mathbf{t}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\frac{\mathbf{m}\mathbf{a}\mathbf{s}\mathbf{s}\mathbf{}\mathbf{c}\mathbf{o}\mathbf{m}\mathbf{p}\mathbf{o}\mathbf{n}\mathbf{e}\mathbf{n}\mathbf{t}}{\mathbf{t}\mathbf{o}\mathbf{t}\mathbf{a}\mathbf{l}\mathbf{}\mathbf{m}\mathbf{a}\mathbf{s}\mathbf{s}}{\mathbf{\times}}{\mathbf{100}}}$

A stock solution of hydrofluoric acid is 15 M and has a density of 0.99 g/mL at 25 °C. What is the mass percent of HF at 25 °C?

a. 15%

b. 30%

c. 45%

d. 60%

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Our tutors have indicated that to solve this problem you will need to apply the Mass Percent concept. You can view video lessons to learn Mass Percent. Or if you need more Mass Percent practice, you can also practice Mass Percent practice problems.

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Our tutors rated the difficulty of*A stock solution of hydrofluoric acid is 15 M and has a dens...*as medium difficulty.

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