Final answer:
To determine the grams of formic acid in a solution with pH of 2.17, we first find the molarity from the pH, then convert this to mass using formic acid's molar mass. Approximately 0.0311 grams of formic acid are present in 100.0 mL of the solution.
Step-by-step explanation:
The student is asking about the concentration of formic acid in a solution with a given pH. To find the grams of formic acid in 100.0 mL of solution with a pH of 2.17, we need to use the pH to calculate the molarity of the solution, then convert that value to mass using the molar mass of formic acid (HCOOH).
Firstly, we calculate the concentration (molarity) of H+ ions in the solution using the pH value:
- pH = -log[H+]
- [H+] = 10-pH
- [H+] = 10-2.17
- [H+] = 6.76 x 10-3 M
Since formic acid is a weak acid and not fully ionized, we consider its percent ionization to determine the actual molarity of the acid. For simplicity, assuming a near similar concentration, we can use this [H+] as an approximation of formic acid molarity.
Next, we use the molar mass of formic acid which is approximately 46.03 g/mol to find the mass:
- Mass (g) = molarity (M) x volume (L) x molar mass (g/mol)
- Mass (g) = 6.76 x 10-3 M x 0.100 L x 46.03 g/mol
- Mass (g) ≈ 0.0311 g
Therefore, there are approximately 0.0311 grams of formic acid in 100.0 mL of the solution with a pH of 2.17.