Buffer Question 1: A 1.00L solution is made of 0.40mol/L NaNO2 and 0.25mol/L HNO2 (K₁ = 4.5 × 10-4). What is the pH of this solution? Buffer Question 2: To this solution, 20.0mL of 0.15 mol/L HNO3 is added. What is the resulting pH? Buffer Question 3: You have a 1.00L acetic acid buffer solution of pH 4.2. If the concentration of potassium acetate is 0.50 mol/L potassium acetate, what is the concentration of the acetic acid? (Ka = 1.8 × 10-5) Buffer Question 4: 250.0 mL of 0.50 mol/L sodium formate is added to 250.0 mL of 0.75 mol/L formic acid. What is the resulting pH of the solution (K₁ = 1.8 × 10-4)

A solution of weak base is titrated to the equivalence point with a strong acid. Which one of the following statements is most likely to be correct? a The pH of the solution at the equivalence point is 7.0. b The pH of the solution is greater than 13.0. c The pH of the solution is less than 2.0. d The pH of the solution is between 2.0 and 7.0. e The pH of the solution is between 7.0 and 13.0. The reason that best supports my choosing the answer above is a Whenever a solution is titrated with a strong acid, the solution will be very acidic. b Because the solution contains a weak base and the acid (titrant) is used up at the equivalence point, the solution will be basic. c Because the solution contains the conjugate acid of the weak base at the equivalence point, the solution will be acidic.

Each symbol in the box below represents a mole of a component in one liter of a buffer solution; represents the anion (X-), = the weak acid (HX), = H+, and =OH. Water molecules and the few H+ and OH- ions from the dissociation of HX and X- are not shown. The box contains 10 mol of a weak acid, , in a liter of solution. Show what happens upon (a) the addition of 2 mol of OH- (2 ). (b) the addition of 5 mol of OH- (5 ). (c) the addition of 10 mol of OH- (10 ). (d) the addition of 12 mol of OH- (12 ). Which addition (a)-(d) represents neutralization halfway to the equivalence point?

8-71 Explain why you do not need to know the chemical formula of a buffer compound to use it.