A solution contains 0.284 M sodium nitrite and 0.257 M nitrous acid. What is the pH of the solution?
Substitute into the Hednderson-Hasselbalch equation and calculate pH.
To find the pH of the solution, we need to convert the concentrations of sodium nitrite (NaNO2) and nitrous acid (HNO2) into their respective equilibrium concentrations of hydroxide (OH-) and hydronium (H3O+) ions. From there, we can calculate the pH using the concentration of hydronium ions.
Step 1: Write the balanced chemical equation for the dissociation of sodium nitrite and nitrous acid in water:
NaNO2 -> Na+ + NO2-
HNO2 -> H+ + NO2-
Step 2: Identify the equilibrium concentrations of hydronium and hydroxide ions:
For sodium nitrite:
[NO2-] = [NaNO2]
For nitrous acid:
[H+] = [HNO2]
Step 3: Use the equilibrium concentrations to calculate the pH:
pH = -log[H3O+]
Let's substitute the given values into the equation and calculate the pH:
[NO2-] = 0.284 M
[H+] = 0.257 M
pH = -log(0.257)
Calculating the logarithm:
pH ≈ -log(0.257)
pH ≈ -(-0.5897)
Finally, we find:
pH ≈ 0.5897
Therefore, the pH of the solution is approximately 0.5897.