17. Carbonyl compounds
A section of Chemistry, 9701
Listing 10 of 304 questions
Hydrogen cyanide, HCN, is a weak acid in aqueous solution. HCNH++ CN–Ka = 6.2 × 10–10 mol dm–3 Calculate the pH of 0.10 mol dm–3 HCN.  pH = Draw a ‘dot-and-cross’ diagram to represent the bonding in the hydrogencyanide molecule. Show the outer shell electrons only.  State the hybridisation of the carbon and nitrogen atoms in hydrogencyanide, and give the H–C–N bond angle. hybridisation of C hybridisation of N H–C–N bond angle  Suggest structures for the organic products A and B in the following reactions. Assume that HCN reacts in a similar way to RCN. HCN H2 + Ni heat with HCl A B  Adding a measured quantity of KCN to a solution of NiCl 2 produces the complex [Ni(CN)2Cl 2]x. Deduce the overall charge, x, on this complex.  x = The complex can exist as two separate isomers with the same geometry around the nickel ion. State the type of isomerism shown by these isomers. If bromide ions are present in the solution, the complex [Ni(CN)2Cl Br]x can form. Assuming that [Ni(CN)2Cl Br]x has the same geometry as [Ni(CN)2Cl 2]x, state the number of isomers of [Ni(CN)2Cl Br]x that could exist, and draw their structures in the box. ● number of isomers of [Ni(CN)2Cl Br]x structures of the isomers of [Ni(CN)2Cl Br]x  An aqueous solution of KCN is gradually added to a solution of NiSO4 until the KCN is in excess. The following series of reactions takes place. NiSO4 more KCN KCN C green precipitate D yellow solution E red solution KCN in excess ● ● The oxidation state of nickel does not change during these reactions. ● ● None of C, D or E contains sulfur. ● ● C contains no potassium. ● ● The K : Ni ratio in D is 2 : 1. ● ● The K : Ni ratio in E is 3 : 1. Use the information to suggest the formulae of C, D and E. C D E  
9701_m18_qp_42
THEORY
2018
Paper 4, Variant 2
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