10. Group 2
A section of Chemistry, 9701
Listing 10 of 275 questions
The most common oxidation states of cobalt are +2 and +3. Complete the electronic configurations of the following free ions. ● Co2+ ���������������������������������������������������������������������������������������������������������������������������� ● Co3+ ����������������������������������������������������������������������������������������������������������������������������  Co2+ and Co3+ both form complexes with edta4–. half-equation E o / V Co3+ + e– Co2+ +1.82 O2 + 4H+ + 4e– 2H2O +1.23 – + e– 2– +0.38 Co2+ + 2e– Co –0.28 Use the data in the table to predict what happens, if anything, when separate aqueous solutions of Co3+ and – are left to stand in the air. aqueous solution of Co3+ aqueous solution of –  Hydrated cobalt(nitrate, Co(NO3)2•6H2O, is a red solid that behaves like hydrated magnesiumnitrate, Mg(NO3)2•6H2O, when heated. Describe in detail what you would expect to observe when crystals of Co(NO3)2•6H2O are heated in a boiling tube, gently at first and then more strongly. Explain why the thermal stability of the Group2 nitrates increases down the group. 
9701_m21_qp_42
THEORY
2021
Paper 4, Variant 2
View
Use Write an equation showing the reaction that occurs when calcium nitrate, Ca(NO3)2, is heated. Describe and explain the trend in thermal stability of the nitrates of the Group II elements. Gently heating ammonium nitrate, NH4NO3, in a test tube produces a mixture of two gases A and B. No residue remains in the tube. The mass spectrum of gas A contains peaks at m/e (mass number) values of 16, 17 and 18, whereas that of gas B has peaks at m/e values of 14, 16, 28, 30 and 44. Identify the peaks in the mass spectra, and suggest the molecular formulae of the gases A and B. Hence suggest an equation for the thermal decomposition of ammonium nitrate.
9701_s07_qp_4
THEORY
2007
Paper 4, Variant 0
View
Questions Discovered
275