Ch 16 Review Answers #14-19

      14. What is the [H⁺] of a solution in which pOH = 7.9?

       1^st find the pH by subtracting 14 – 7.9 = 6.1; Use the pH as a negative exponent

       1.0 x 10^-6

15. Which of the following pairs would make a buffer?

            a. HCOOH, HCOO¯ or HCOOH, HCOONa The conjugate base can be missing the acidic H and have a negative sign, or the acidic H can be replaced by any cation.

            b. H₂SO₄, SO₄²¯

            c. C₂H₂O₂¯, H⁺

            d. NO₃¯, H⁺

            e. Na⁺, C₂H₂O₂

     16. Determine the volume of 0.100 M KOH needed to titrate 50.0 mL of 0.200 M

           HNO₃.

                  M₁V₁ = M₂V₂                    V₁ = M₂V₂                  V₁ = (50.0 mL)(0.200 M)

                                                            M₁                                                   0.100 M

                                                                                    V₁ = 100. mL

17. What is the conjugate base of a weak acid? the conjugate acid of a weak base?

      They are the opposite. A weak acid has a strong conjugate base. A weak base has a strong conjugate acid

18. What is the formula for the k_w of a neutral solution?

     K_w =  [H+] [OH-]

19. Name 2 weak acids.

      HF, hydrofluoric acid and HC₂H₃O₂ acetic acid, Any acid with carbon