Question

28. CN, NH3, and some other compounds and ions will bind to transition metal ions and make them more soluble. The cyanide is acting like a: a. Bronsted acid b. Bronsted base c. Lewis acid d. Lewis base 29. Which solution, formed by mixing, would maintain a fairly constant pH even when additional small amounts of a strong acid or a strong base are added? 100 mL of 1 M HCl and 100 mL of 1 M NaOH b. 100 mL of 1 M NH4Cl and 100 mL of 1 M NH3 c. 100 mL of 1 M NaOH and 100 mL of 1 M NH3 d. 100 mL of 1 M HCl and 100 mL of 1 M NaCl 30. A Bronsted acid is Ca. a proton donor b. a proton acceptor C. it increases the hydrogen ion concentration d. an electron pair acceptor Arrhenius acid is: noontration

Answer 1

28. CN^- , NH₃ and some other compounds and ion will bind to a transition metal ions and make them more possible. The Cyanide is acting like a

ans) b)  BRONSTED BASE.

Explanation : A Solution which accept protons, and these protons are Hydrogen ions(H⁺). This is Solution is a Bronsted Base. In common transition metal ions are insoluble. While adding Bronsted bases transtition metal ions become more soluble. Here the examples are mentioned as CN^- and NH₃

Example : When Octa hedral hexa aqua copper(II) reacts with NH₃ make soluble tansition metal ions

[Cu(H₂O)₆]²⁺_(aq) + 2NH_3(aq) ---------> [Cu(OH)₂(H₂O)₄]_(s) + 2NH₄⁺_(aq)

blue precipitate soluble in excess NH₃

  Cu(OH)₂(H₂O)₄]_(s) +4NH₃ -----------> [Cu(NH₃)₄(H₂O₂)₆]²⁺_(aq) + 2H₂O(I) + 2OH^-(aq)

royal blue solution

29. Which solution formed by mixing would maintain a fairly constant pH even additional small amounts of a strong acid or a strong base are added

ans) a) 100ml of 1M HCl and 100ml of 1M NaOH

Explanation : While adding some additional amount of strong acid or a strong base the pH will be constant while mixing 100ml of 1M HCl and 100ml of 1M NaOH.

When a strong acid(HCl) reacts with the strong base(NaOH), HCl donates ions whereas NaOH accepts ions. This means the acid and base molecules entirely separate into ions. While attaining the equivalent point there will be a formation of hydrogen and hydroxide ions in equal proportion, they then associate to form H₂O. pH of water is 7, which is neutral. So after reaching this neutral point there will be no change in the pH while adding more acid or base.

30. A Bronsted Acid is a

ans) a) Proton donor

Explanation: If a Substance is capable of donating a Proton ie., a Hydrogen ion(H⁺). It results to form a conjugate base.

Example :

When Acetic acid reacts with ammonia, it donates a proton to ammonia to form a conjugate base.

CH₃COOH +NH₃ ------> NH₄⁺  +     CH₃COO^-

  acid Conjugate base