Chemistry Answer Note #75

Question 1 4. Name the compound using IUPAC Nomenclature (2 points) (CH3)2CHCH2CH2CH(CH2CH3)CH2C(CH3)3 Answer The name of the given compound, following the IUPAC nomenclature, is 2,3,4,5,6pentamethylheptane. Explanation: In order to name this compound, we must first identify the longest carbon chain. In this case, that is the 7-carbon chain. Next, we must number the carbons starting from one end of the chain, so that the substituents have the lowest possible number. In this case, it is more convenient to number the chain from the left, thus giving the first substituent (CH3)2 a locant of 2, the second substituent CH2 a locant of 3, and so on. This results in the compound being named as 2,3,4,5,6-pentamethylheptane. Question 2 (b) Study the flow chart below and answer the questions that follow. (i) Write an equation for the formation of solid A and gas B. (1 mark) ……………………………………………………………………………………………… …………………………… (ii) Name; Solution C ………………………………………………….. (1 mark) Solid D ………………………………………………….. (1 mark) (c) Write the formula of the complex ion in solution E. (1 mark) ……………………………………………………………………………………………… …………………………… 4. Study the flow chart below and answer the questions that follow. (a) Name substance. (3 marks) X …………………………………………………………………. Q …………………………………………………………………. R …………………………………………………………………. (b) Write down an equation for the reaction represented by step III. (1 mark) ……………………………………………………………………………………………… …………………………… (c) What are the conditions and reagent required for steps? (i) I (2 marks) Reagent ………………………………………………………………………………….. Condition - ………………………………………………………………………………….. (ii) IV (2 marks) Reagent ………………………………………………………………………………….. Condition - ………………………………………………………………………………….. (b) Name the process represented by: (4 marks) I ………………………………………………………………………. II ………………………………………………………………………. IV ………………………………………………………………………. V ………………………………………………………………………. Answer (b) Study the flow chart below and answer the questions that follow. (i) Write an equation for the formation of solid A and gas B. (1 mark) The formation of solid A and gas B occurs through the reaction of solution C and solid D. C(s) + D(s) → A(s) + B(g) (ii) Name; Solution C - Copper(II) sulfate solution Solid D - Zinc metal (c) Write the formula of the complex ion in solution E. (1 mark) Solution E contains a complex ion of Cu(NH3)4^2+ 4. Study the flow chart below and answer the questions that follow. (a) Name substance. (3 marks) X - Zinc metal Q - Zinc sulfate solution R - Hydrogen gas (b) Write down an equation for the reaction represented by step III. (1 mark) The reaction in step III is the reaction of zinc metal with sulfuric acid to form zinc sulfate and hydrogen gas. Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) (c) What are the conditions and reagent required for steps? (i) I (2 marks) Reagent - Zinc metal Condition - Aqueous sulfuric acid (ii) IV (2 marks) Reagent - Copper(II) sulfate solution Condition - Zinc metal (b) Name the process represented by: (4 marks) I - Single Displacement Reaction II - None IV - Double Displacement Reaction V - Combination Reaction Question 3 2. Use the information below to answer the questions that follow. The letters are not the actual symbols of the elements. Element Atomic No. M.P0C B.P0C Ionic radius (nm) P 11 98 890 0.095 Q 12 650 1110 0.065 R 13 660 2470 0.050 S 14 1410 2360 0.041 T 15 44.2 & 590 280 0.034 U 16 113 & 119 445 0.184 V 17 -101 -35 0.181 W 18 189 -186 - (a) (i) Write the electronic configuration of the atoms represented by letters T and W. (1 mark) (ii) State the nature of the oxides of the elements represented by Q and U. (2 marks) ……………………………………………………………………………………………… ………………. ……………………………………………………………………………………………… ………………. (b) Why does the elements represented by the letters T and U have two values of melting points? (1 mark) ……………………………………………………………………………………………… …………………………… (c) Explain the following observations in terms of structure and bonding. (i) There is an increase in boiling point from P to R. (2 marks) ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… (ii) Element S has a high boiling point. (2 marks) ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… (iii) There is a decrease in boiling points from U to W. (2 marks) ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… ……………………………………………………………………………………………… …………………………… (d) (i) Compare the atomic radius of U and V. Answer (a)(i) The electronic configuration of the atom represented by T is [He] 2s2 2p3. The electronic configuration of the atom represented by W is [Ne] 3s2 3p5. (ii) The nature of the oxides of the element represented by Q is ionic, while the nature of the oxides of the element represented by U is covalent. (b) The elements represented by the letters T and U have two values of melting points due to the presence of different allotropes. These elements are able to exist in multiple forms with different crystal structures, resulting in different melting points. (c)(i) The increase in boiling point from P to R can be explained by the change in bonding type and strength. As you move from P to R, the elements transition from metallic bonding to covalent bonding. Covalent bonds are stronger and require more energy to break, resulting in a higher boiling point. (ii) Element S has a high boiling point due to its high electronegativity, which results in strong intermolecular forces between its molecules. (iii) The decrease in boiling points from U to W can be explained by the increase in atomic size. As you move from U to W, the atomic radius increases, leading to weaker intermolecular forces and a decrease in boiling point. Sources: - "Chemistry: The Molecular Nature of Matter and Change" by Martin Silberberg - "General Chemistry: Principles and Modern Applications" by Ralph H. Petrucci, F. Geoffrey Herring, Jeffry D. Madura, and Carey Bissonnette (d) (i) The atomic radius of U is larger than V. This can be attributed to the higher number of protons in V, which results in a stronger pull on the electrons and a smaller atomic radius.