Chapter 25, Problem 2ASA

1. The pH of a 0.1 M solution of a monobasic acid P is 1.0 while the pH of a 0.2 M solution of another monobasic acid Q is 3.4. (a) Which, P or Q. is a more concentrated solution? (b) Which, P or Q. is a stronger acid? (c) Which, P or Q, will react faster when a piece of magnesium is dropped to them? (d) Which, P or Q, contains more H'(aq) ions in 50 cm' solution? (e) Which, P or Q or both, can be neutralized by an alkali? (f) Name an instrument to measure the pH of the above solutions. (g) Is Pa strong acid? Explain your answer.

Consider two acids: HCO2H (formic acid, pKa = 3.8) and pivalic acid [(CH3)3CCO,H, pK = 5.0]. (a) Which acid has the larger K? (b) Which acid is the stronger acid? (c) Which acid forms the stronger conjugate base? (d) When each acid is dissolved in water, for which acid does the equilibrium lie further to the right? %3D The pKa values in Table 2.1 span a large range (-7 to 50). The pK, scale is logarithmic. small difference in pK, translates into a large numerical difference, For example, the diffe between the pK, of NH3 (38) and CH2=CH, (44) is six pKa units. This means that NH, is one million times more acidic than CH,=CH,.

30. In the reaction HCl(aq) + H₂O(l) ⇒Cl¯(aq)+ H3O+ (aq) does water act as a Brønsted-Lowry acid, a Brønsted-Lowry base, or neither, or both? (A) Neither as an acid nor as a base; water is neutral (B) Both an acid and a base. (C) An acid (D) A base (E) Depends temperature