Which of the following is a Lewis acid? A) Fe3* B) CN C) NH3 D) SCN

Chloroacetic acid, HC2H2ClO2, has a greater acid strength than acetic acid, because the electronegative chlorine atom pulls electrons away from the OH bond and thus weakens it. Calculate the hydronium-ion concentration and the pH of a 0.0020 M solution of chloroacetic acid, Ka is 1.3 103.

Acids You make a solution by dissolving 0.0010 mol of HCl in enough water to make 1.0 L of solution. a Write the chemical equation for the reaction of HCl(aq) and water. b Without performing calculations, give a rough estimate of the pH of the HCl solution. Justify your answer. c Calculate the H3O+ concentration and the pH of the solution. d Is there any concentration of the base OH present in this solution of HCl(aq)? If so, where did it come from? e If you increase the OH concentration of the solution by adding NaOH, does the H3O+ concentration change? If you think it does, explain why this change occurs and whether the H3O+ concentration increases or decreases. f If you were to measure the pH of 10 drops of the original HCl solution, would you expect it to be different from the pH of the entire sample? Explain. g Explain how two different volumes of your original HCl solution can have the same pH yet contain different moles of H3O+. h If 1.0 L of pure water were added to the HCl solution, would this have any impact on the pH? Explain.

1. Which of the following can act as a Lewis acid? (Hint : In each case, draw the Lewis electron dot structure of the molecule or ion. Are there lone pairs of electrons on the central atom? If so, it can be a Lewis base. Does the central atom lack an electron pair? If so, it can behave as a Lewis acid.) PH3 BCl3 H2S HS−

Hypofluorous acid, HOF, is known, but fluorous acid, HOFO, is not. Which acid would you expect to be stronger?

The base ethylamine (CH3CH2NH2) has a Kb of. A closely related base, ethanolamine(HOCH2CH2NH2), has a Kb of 3.2105. (a) Which of the two bases is stronger? (b) Calculate the pH of a 0.10M solution of the strong base?

For oxyacids, how does acid strength depend on a. the strength of the bond to the acidic hydrogen atom? b. the electronegativity of the element bonded to the oxygen atom that bears the acidic hydrogen? c. the number of oxygen atoms? How does the strength of a conjugate base depend on these factors? What type of solution forms when a nonmetal oxide dissolves in water? Give an example of such an oxide. What type of solution forms when a metal oxide dissolves in water? Give an example of such an oxide.

Calculate the pH and the pOH of each of the following solutions at 25 C for which the substances ionize completely: (a) 0.000259 M HClO4. (b) 0.21 M NaOH. (c) 0.000071 M Ba(OH)2. (d) 2.5 M KOH

What two common assumptions can simplify calculation of equilibrium concentrations in a solution of a weak acid?

Methylammonium chloride is a salt of methylamine, CH3NH2. A 0.10 M solution of this salt has a pH of 5.82. a Calculate the value for the equilibrium constant for the reaction CH3NH3++H2OCH3NH2+H3O+ b What is the Kb value for methylamine? c What is the pH of a solution in which 0.450 mol of solid methylammonium chloride is added to 1.00 L of a 0.250 M solution of methylamine? Assume no volume change.