10. Group 2
A section of Chemistry, 9701
Listing 10 of 275 questions
The table lists values of solubility products, Ksp, of some Group 2 carbonates. solubility product in water at 298 K, Ksp / mol2 dm–6 MgCO3 1.0 × 10–5 CaCO3 5.0 × 10–9 SrCO3 1.1 × 10–10 Use the data in the table to describe the trend in the solubility of the Group 2 carbonates down the group. Write an equation to show the equilibrium for the solubility product for MgCO3. Include state symbols. With reference to your equation in , suggest what is observed when a few cm3 of concentrated Na2CO3are added to a saturated solution of MgCO3. Explain your answer. Use the data in the table to calculate the solubility of MgCO3 in water at 298 K, in g dm–3. solubility of MgCO3 = g dm–3 Magnesium nitrate decomposes at a lower temperature than barium nitrate. Explain why. A sample of barium nitrate was heated strongly until no further change occurred. A white solid was formed. Write an equation for the action of heat on barium nitrate. When water was added to the white solid produced in , an alkaline solution was produced. Adding sulfuric acid to this solution produced a white precipitate. Write equations to explain these observations.
9701_w17_qp_41
THEORY
2017
Paper 4, Variant 1
View
Describe and explain how the density and melting point of cobalt compare to those of calcium. density of cobalt explanation melting point of cobalt explanation Transition metals can form complexes. What is meant by the term transition metal complex? Cobalt can form the compounds [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br. These two compounds are structural isomers. Define the term structural isomer. Draw a three-dimensional diagram to show the structure of the ion [Co(NH3)5Br]2+. Name its shape. [Co(NH3)5Br]2+ shape State the type of bonding between the cobalt ion and NH3 groups in the [Co(NH3)5Br]2+ ion. State the oxidation number of cobalt in ● [Co(NH3)5Br]2+ oxidation number of Co = ● [Co(NH3)5SO4]+ oxidation number of Co = Solutions of the compounds [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br can be distinguished from each other by simple chemical tests. Assume that any species bonded to the cobalt ion does not react in these tests. Complete the table with two different tests that could be used to positively identify each compound. Give the expected observation with each compound. test observation with [Co(NH3)5Br]SO4observation with [Co(NH3)5SO4]Br The two compounds [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br are different colours. Explain why the colours of the two compounds are different. Some transition metals and their compounds act as catalysts. The catalysis can be classified as heterogeneous or homogeneous. Complete the table by placing one tick () in each row to indicate the type of catalysis in each reaction. heterogeneous homogeneous Fe in the Haber process Fe2+ in the I– / S2O8 2– reaction NO2 in the oxidation of SO2 V2O5 in the Contact process
9701_w17_qp_41
THEORY
2017
Paper 4, Variant 1
View
When water is added to magnesium nitride, Mg3N2, the products are a white suspension of Mg(OH)2 and an alkaline gas. Write an equation for this reaction. A 2.52 g sample of Mg3N2 is added to an excess of water. Calculate the mass of Mg(OH)2 formed. mass of Mg(OH)2 = g State and explain how the solubility of the Group2 hydroxides varies down the group. Magnesiumhydroxide is sparingly soluble in water. The concentration of its saturated solution at 298 K is 1.7 × 10–4 mol dm–3. Write an expression for the solubility product, Ksp, of Mg(OH)2. Ksp = Calculate the value of Ksp for Mg(OH)2 at 298 K and state its units. Ksp = units The temperature at which the Group2 hydroxides and carbonates start to decompose increases down the group. Suggest an explanation for this trend in the decomposition temperature of the Group 2 hydroxides.
9701_w17_qp_42
THEORY
2017
Paper 4, Variant 2
View
The table lists values of solubility products, Ksp, of some Group 2 carbonates. solubility product in water at 298 K, Ksp / mol2 dm–6 MgCO3 1.0 × 10–5 CaCO3 5.0 × 10–9 SrCO3 1.1 × 10–10 Use the data in the table to describe the trend in the solubility of the Group 2 carbonates down the group. Write an equation to show the equilibrium for the solubility product for MgCO3. Include state symbols. With reference to your equation in , suggest what is observed when a few cm3 of concentrated Na2CO3are added to a saturated solution of MgCO3. Explain your answer. Use the data in the table to calculate the solubility of MgCO3 in water at 298 K, in g dm–3. solubility of MgCO3 = g dm–3 Magnesium nitrate decomposes at a lower temperature than barium nitrate. Explain why. A sample of barium nitrate was heated strongly until no further change occurred. A white solid was formed. Write an equation for the action of heat on barium nitrate. When water was added to the white solid produced in , an alkaline solution was produced. Adding sulfuric acid to this solution produced a white precipitate. Write equations to explain these observations.
9701_w17_qp_43
THEORY
2017
Paper 4, Variant 3
View
Describe and explain how the density and melting point of cobalt compare to those of calcium. density of cobalt explanation melting point of cobalt explanation Transition metals can form complexes. What is meant by the term transition metal complex? Cobalt can form the compounds [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br. These two compounds are structural isomers. Define the term structural isomer. Draw a three-dimensional diagram to show the structure of the ion [Co(NH3)5Br]2+. Name its shape. [Co(NH3)5Br]2+ shape State the type of bonding between the cobalt ion and NH3 groups in the [Co(NH3)5Br]2+ ion. State the oxidation number of cobalt in ● [Co(NH3)5Br]2+ oxidation number of Co = ● [Co(NH3)5SO4]+ oxidation number of Co = Solutions of the compounds [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br can be distinguished from each other by simple chemical tests. Assume that any species bonded to the cobalt ion does not react in these tests. Complete the table with two different tests that could be used to positively identify each compound. Give the expected observation with each compound. test observation with [Co(NH3)5Br]SO4observation with [Co(NH3)5SO4]Br The two compounds [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br are different colours. Explain why the colours of the two compounds are different. Some transition metals and their compounds act as catalysts. The catalysis can be classified as heterogeneous or homogeneous. Complete the table by placing one tick () in each row to indicate the type of catalysis in each reaction. heterogeneous homogeneous Fe in the Haber process Fe2+ in the I– / S2O8 2– reaction NO2 in the oxidation of SO2 V2O5 in the Contact process
9701_w17_qp_43
THEORY
2017
Paper 4, Variant 3
View
Questions Discovered
275