9.2. Periodicity of chemical properties of the elements in Period 3
A subsection of Chemistry, 9701, through 9. The Periodic Table: chemical periodicity
Listing 10 of 224 questions
Chlorine, Cl 2, reacts with many elements and compounds to form chlorides. Table 2.1 shows information about some chlorides of Period 3 elements. Table 2.1 Na Mg Si formula of chloride structure of chloride giant bonding of chloride covalent pH of solution formed on addition of chloride to water 6.2 Complete Table 2.1. When Cl 2 reacts with cold NaOH, Cl 2 is both oxidised and reduced. The products are NaCl, water and G. State the type of redox reaction in which the same species is both oxidised and reduced. Identify G. Write an equation for the reaction between Cl2 and hot NaOH. Describe fully what is observed when AgNO3is added to the aqueous solution of the chloride of sodium, followed by dilute NH3. An excess of Cl 2 reacts with phosphorus to form PCl 5. PCl 5 is a simple molecule in the gas phase. It also exists in a solid form as two ions, PCl4 + and PCl 6 –. Complete Table 2.2 to identify the shapes of each of these species. Table 2.2 species PCl5 PCl4 + PCl6 – shape tetrahedral PCl5 reacts with J to form H3PO4. Identify J and state the type of reaction. J type of reaction Cl 2 reacts readily with propene to form K, 1,2-dichloropropane. K can be used to form L. Cl2 Cl Cl Cl propene K L reaction 1 reaction 2 Complete to show the mechanism for the reaction of Cl 2 with propene in reaction 1. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. C H H H CH3 C C C CH3 H H H Cl Cl Cl Cl Identify the reagent and conditions for reaction 2. Draw one repeat unit of the addition polymer that forms from L.
9701_m24_qp_22
THEORY
2024
Paper 2, Variant 2
View
Use This question is about the properties and reactions of the oxides of some elements in their +4 oxidation state. Chlorine dioxide, Cl O2, is an important industrial chemical, used to bleach wood pulp for making paper, and to kill bacteria in water supplies. However, it is unstable and decomposes into its elements as follows. 2Cl O2Cl 2+ 2O2The chlorine atom is in the middle of the Cl O2 molecule. Using the chlorine-oxygen bond energy as 278 kJ mol–1, and other values from the Data Booklet, calculate DH for the above reaction. DH = kJ mol–1 Assuming the Cl -O bonds in chlorine dioxide are double bonds, predict the shape of the Cl O2 molecule. Explain your answer. Cl O2 can be made in the laboratory by reacting KCl O3 with concentrated H2SO4. Other products are K2SO4, KCl O4 and H2O. Construct a balanced equation for this reaction. You may find the use of oxidation numbers helpful. Sulphur dioxide is an atmospheric pollutant. State two sources of atmospheric SO2 that arise from human activity. Explain why SO2 is a pollutant, and state an environmental consequence of this pollution. Examiner’s Use All the oxides of the elements in Group IV in their +4 oxidation state are high melting point solids except CO2. Explain this observation by describing the bonding in CO2, SiO2 and SnO2. State the difference in the thermal stabilities of SnO2 and PbO2. Illustrate your answer with an equation. CO2 dissolves in water to form a weakly acidic solution containing the hydrogencarbonate ion. Write an equation for the reaction of CO2 with water, and write an expression for the equilibrium constant, Kc. Explain the role of the hydrogencarbonate ion in controlling the pH of blood, illustrating your answer with relevant equations.
9701_s08_qp_4
THEORY
2008
Paper 4, Variant 0
View
Questions Discovered
224