Zadanie 34
Which species behaves as a Lewis base in the following reaction? Cl− + AlCl3 → AlCl4− A. Cl− B. AlCl3 C. AlCl4− D. Both Cl− and AlCl3
Lewis acids and bases
Define a Lewis acid as an electron-pair acceptor and a Lewis base as an electron-pair donor, apply the theory to inorganic reactions such as BF3 with NH3 and to organic reactions, and identify the Lewis acid and base in each.
Tę umiejętność sprawdza 15 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Zadania sprawdzające tę umiejętność: 15 Otwórz w wyszukiwarce z filtrami
Zadanie 36
Which statement explains the Lewis acid-base nature of the carbocation in this reaction? C2H5+ + I− → C2H5I A. Lewis base because it accepts a pair of electrons B. Lewis base because it donates a pair of electrons C. Lewis acid because it donates a…
Zadanie 3b
(i) Outline the way in which ammonia behaves as a Lewis base during the formation of the complex ion [Ag(NH3)2]+(aq). (ii) Determine the pH at 298 K of an aqueous ammonia solution of concentration 0.180 mol dm−3. Use section 1 of the data…
Zadanie 37
Which term cannot describe the chloride ion, Cl−? A. Lewis base B. ligand C. Brønsted–Lowry acid D. nucleophile
Zadanie 6c
The complex ion [Cr(H2O)6]3+ is violet and absorbs light most strongly at about 580 nm. The complex ion [Cr(NH3)6]3+ is orange and absorbs light most strongly at about 465 nm. (i) Explain why the two complex ions have different colours. Use…
Zadanie 3d
Boron trifluoride, BF3, reacts with ammonia to form the adduct F3B−NH3, in which a coordination bond joins the boron atom to the nitrogen atom. Deduce whether the boron atom in BF3 acts as a nucleophile or an electrophile, and as a Lewis…
Zadanie 6b
The nitrite ion, NO2−, can form complexes with transition element ions such as Co3+ and Ni2+. Describe the type of bonding between the nitrite ion and the metal ion in such a complex, and state the role of the nitrite ion in acid-base…
Zadanie 37
Boron trifluoride reacts with ammonia to form an adduct. BF3 + NH3 → H3N−BF3 Which terms describe boron trifluoride in this reaction? A. Electrophile and Lewis base B. Nucleophile and Lewis acid C. Nucleophile and Lewis base D. Electrophile and Lewis…
Zadanie 5d
In the gas phase, some AlCl3 molecules join in pairs to form this dimer: (i) Identify the hybridization of the aluminium atom in the dimer, Al2Cl6. (ii) Describe, in terms of Lewis acids and bases, how two AlCl3 molecules bond together to…
- Materiał graficzny
Zadanie 5d
In the gas phase some aluminium chloride exists as the dimer Al2Cl6, the structure of which is shown below. (i) Identify the hybridization of the aluminium atom in the dimer, Al2Cl6. (ii) Describe, in terms of Lewis acid–base behaviour, the…
- Materiał graficzny
Zadanie 4d
Aluminium salts form acidic solutions owing to equilibria such as: Al3+(aq) + H2O(l) ⇌ Al(OH)2+(aq) + H+(aq) Comment on the role of Al3+ in forming the Al(OH)2+ ion, in acid-base terms.
Zadanie 7a
(i) State why ammonia can act as a Lewis base. (ii) Calculate the pH of a 2.50 × 10−2 mol dm−3 aqueous solution of ammonia. pKb = 4.75 at 298 K. (iii) Justify whether a 1.0 dm3 solution made by mixing 0.30 mol NH3…
Zadanie 26
Boron trifluoride reacts with ammonia as shown. BF3 + NH3 → F3B−NH3 Which statement is correct? A. NH3 is a Lewis acid because it donates a pair of electrons B. BF3 is a Lewis base because it donates a pair of electrons C. NH3 is a…
Zadanie 27
Which of these species can act as both a Lewis base and a Brønsted–Lowry base? I. CH3NH2 II. BF3 III. H2O A. I and II only B. I and III only C. II and III only D. I, II and III
Zadanie 27
Which species can act as a Lewis base but not as a Lewis acid? A. BF3 B. Fe3+ C. NH3 D. H+