3. Chemical bonding
A section of Chemistry, 9701
Listing 10 of 239 questions
Complete the table to show the total number of unpaired electrons in the 3d and 4s orbitals of each isolated gaseous atom. number of unpaired electrons 3d 4s Cr Mn Fe  Solid potassium manganate(, KMnO4, decomposes on heating to form manganese(oxide, potassiummanganate(and a colourless gas. Construct an equation for this reaction. Explain the origin of colour in transition element complexes. The reaction scheme shows some reactions of [Cu(H2O)6]2+. [Cu(H2O)6]2+ precipitate A solution of B CuCO3NaOHreaction 3 reaction 2 reaction 1 excess NH3solution of C reaction 4 CH3CO2HWrite the formulae of precipitate A, complex ion B, compound C  Identify a suitable reagent for reaction3. Write an equation for reaction4. Describe two visual observations that would be made during reaction 4. Platin, Pt(NH3)2Cl 2, is a neutral complex of platinum(. Explain why Pt(NH3)2Cl 2 has no charge. Pt(NH3)2Cl 2, displays cis-trans isomerism. Draw the structure of trans-platin. State its shape and the Cl –Pt–Cl bond angle. shape Cl –Pt–Cl bond angle  Cis-platin is an effective anti-cancer drug. Describe the action of cis-platin in this role. The use of cis-platin can cause side effects so nedaplatin has been developed. Nedaplatin can be synthesised from cis‑platin, Pt(NH3)2Cl 2, by replacing the two chloride ion ligands with a single bidentate ligand as shown. Suggest the structure for nedaplatin. O– –O O Pt(NH3)2Cl 2 cis-platin + nedaplatin  
9701_w18_qp_41
THEORY
2018
Paper 4, Variant 1
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Complete the table to show the total number of unpaired electrons in the 3d and 4s orbitals of each isolated gaseous atom. number of unpaired electrons 3d 4s Cr Mn Fe  Solid potassium manganate(, KMnO4, decomposes on heating to form manganese(oxide, potassiummanganate(and a colourless gas. Construct an equation for this reaction. Explain the origin of colour in transition element complexes. The reaction scheme shows some reactions of [Cu(H2O)6]2+. [Cu(H2O)6]2+ precipitate A solution of B CuCO3NaOHreaction 3 reaction 2 reaction 1 excess NH3solution of C reaction 4 CH3CO2HWrite the formulae of precipitate A, complex ion B, compound C  Identify a suitable reagent for reaction3. Write an equation for reaction4. Describe two visual observations that would be made during reaction 4. Platin, Pt(NH3)2Cl 2, is a neutral complex of platinum(. Explain why Pt(NH3)2Cl 2 has no charge. Pt(NH3)2Cl 2, displays cis-trans isomerism. Draw the structure of trans-platin. State its shape and the Cl –Pt–Cl bond angle. shape Cl –Pt–Cl bond angle  Cis-platin is an effective anti-cancer drug. Describe the action of cis-platin in this role. The use of cis-platin can cause side effects so nedaplatin has been developed. Nedaplatin can be synthesised from cis‑platin, Pt(NH3)2Cl 2, by replacing the two chloride ion ligands with a single bidentate ligand as shown. Suggest the structure for nedaplatin. O– –O O Pt(NH3)2Cl 2 cis-platin + nedaplatin  
9701_w18_qp_43
THEORY
2018
Paper 4, Variant 3
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Define the term transition element. Complete the electronic configuration of an isolated gaseous Fe3+ ion. 1s2 Name two transition elements whose isolated gaseous atoms have the same number of electrons in the 3d subshell as an isolated gaseous Fe3+ ion. Cobalt(sulfate is added to water to form a pink solution containing complex ion P. An excess of concentrated hydrochloricacid is added to this solution to form a blue solution containing complex ion Q. Complete the diagram to show the three-dimensional structure of Q. State the charge on this complex ion. Co charge  Name the type of reaction in which P forms Q. Explain why solutions that contain transition element ions are often coloured. Explain why the colours of P and Q are different. A solution of the bidentate ligand 1,2‑diaminoethane, H2NCH2CH2NH2, is added to an aqueous solution of cobalt(sulfate. Oxygen is then bubbled into the mixture forming a complex ion with the formula [Co(H2NCH2CH2NH2)3]3+. This complex ion exists as a mixture of two isomers. The geometry of both of these isomeric complexes is octahedral. In this reaction, cobalt undergoes two types of reaction. One type of reaction is the same as that described in . Name the other type of reaction that cobalt undergoes. Draw the three-dimensional structures of the two isomeric complexes in the boxes. You may use N N to represent a molecule of H2NCH2CH2NH2. Co Co  Name the type of stereoisomerism shown by these two isomeric complexes. State the co-ordination number of cobalt in these two isomeric complexes. The stability constants, Kstab, of three complexes of mercury(are given in the table. complex Kstab [Hg(CN)4]2– 2.5 × 1041 [HgCl 4]2– 1.7 × 1016 2– 2.0 × 1030 Write an expression for the Kstab of [Hg(CN)4]2–. Kstab =  An aqueous solution containing Hg2+ is added to a solution containing equal concentrations of CN–, Cl –and I–. The mixture is left to reach equilibrium. Predict which of the complexes [Hg(CN)4]2–, [HgCl 4]2– and 2– is present in the resulting mixture in the highest concentration and which is present in the lowest concentration. Explain your answer. 
9701_w20_qp_42
THEORY
2020
Paper 4, Variant 2
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Questions Discovered
239