CH 110

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Copperbelt University *

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INORGANIC

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Chemistry

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Nov 24, 2024

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QUESTION ONE: ORGANIC CHEMISTRY 1. Draw the structural formulas for the following compounds: [3] a) 3,3,6,6-tetramethyl-4-octyne b) 2-bromo-1-tert-butylcylopropane c) 3-ethyl-2, 3-dimethyl-2-pentanol 2. Draw any two possible structures for the following molecular formula and name them C 5 H 12 O [2] 3. Answer the following question on aromatic compounds [3] a) Identify the import characteristics of an aromatic compound b) What is the major property given the reagent below? 4. Draw the structure of the compound with three carbon atoms that belongs to each of the following families of organic compounds: [4] a) Aldehydes b) Ketones c) Carboxylic acids d) Ether 5. Give the structure of the product(s) resulting from the oxidation of each of the following alcohols/aldehydes and name them: [3] a) 3-methyl-2-butanol b) 2-methyl-2-butanol c) 2-methylcyclopentanol 6. Draw the structure of the major products for each of the following reactions: [3] a) CH 3 CH 2 CH = CH 2 + H 2 O Pt → b) CH 3 CH 2 CH = CH 2 + Br → c) CH 3 CH 2 CH = CH + 2 HBr → 7. What carboxylic acid and alcohol are required to produce the following ester? [1] 8. Complete the following esterification reaction: [1]

[20 TOTAL MARKS] QUESTION TWO 1. State Hess’s law? [2] 2. Consider the following reaction [3] 2 M g ( s ) + O 2 ( g ) → 2 MgO ( s ) ∆ H =− 1204 KJ i. Calculate the amount of heat transferred when 2.4g of M g ( s ) reacts at constant pressure. ii. How many grams of MgO ( s ) are produced during an enthalpy change of ∆ H = 96 KJ ? iii. How many Kilo joules of heat are absorbed when 7.50 g of MgO ( s ) are decomposed into M g ( s ) ∧ O 2 ( g ) at constant pressure. 3. From the following enthalpies of reaction; [6] H 2 ( g ) + F 2 ( g ) → 2 HF ( g ) ∆ H =− 537 KJ C ( s ) + F 2 ( g ) →C F 2 ( g ) ∆ H =− 680 KJ 2 C ( s ) + 2 H ( g ) →C 2 H 4 ( g ) ∆H =− 52.3 KJ Calculate the ∆ H for the reaction of C 2 H 4 ( g ) 4. Identify each process as endothermic or exothermic and indicate the sign of ∆ H . [3] i. Sweat evaporating from skin ii. Water freezing in a freezer iii. Wood burning in fire 5. Write thermodynamic equations corresponding to the following description [3] i. The standard enthalpy of formation of iron (III) oxide at 298 k is -824.2 KJ/mole ii. The standard enthalpy change at 298K for the reaction between gaseous phosphorous trichloride and chlorine gas to give gaseous phosphorus pentachloride is -84.3 KJ iii. The standard enthalpy OF COMBUSTIONOF LIQUID ethanol is -1368 KJ/mole 6. When 6.5 g sample of solid NaOH dissolves in100.00g of water in a coffee-cup calorimeter, the temperature rises from 21.6 ℃ to 37.8 ℃ . Calculate the ∆ H (in KJ/mole) for the solution process. (Assume the specific heat of the solution formed is 4.18 J/g-K)

− ¿ [ 3 ] + ¿ + OH ( aq ) ¿ NaO H ( s ) → Na ( aq ) ¿ [20 TOTAL MARKS] QUESTION THREE 1. Predict which bond in each of the following groups will be the most polar: [4] i. C - F, Si - F, Ge – F ii. P - CI, S-CI iii. S - F, S - Cl, S – Br iv. Ti - Cl, Si - Cl, Ge - Cl 2. With an example in each case, explain situations where a molecule that contains polar bonds can be nonpolar. [5] 3. Draw the Lewis electron dot structures for these molecules, including resonance structures where appropriate: [6] i. C S 3 − 2 ii. C S 2 iii. Predict the molecular shapes for C S 3 − 2 and C S 2 4. Name the dominant (strongest) intermolecular force in the following pairs. [3] i. Methane and methane ii. Ethanol and ethanol iii. HCI and HCI 5. Use the following data to estimate the enthalpy of formation (AHO) for potassium chloride

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K ( s ) + 1 2 C I 2 ( g ) →KC I ( s ) [2] Lattice energy -690 kJ/mol Ionization energy for K 735 kJ/mol Electron affinity of C -349 kJ/mol Bond energy of C I 2 239 kJ/mol Enthalpy of sublimation for K 64 kJ/mol [20 TOTAL MARKS] QUESTION FOUR 1. Bellow: [8] i. State the Five Steps involved in Scientific method. ii. Distinguish between extensive and intensive properties of matter iii. Perform Mathematical operations and express each result to the correct number of significant Figures a) 0.1054 + 2.07 − 2.114 b) 8.27 ( 4.987 − 4.962 ) 2. a) In an experiment to make crystals of hydrated Copper (II) nitrate, a sample of 5.60 g of Copper (II) oxide was added to 7.878g nitric acid. [9] i. calculate the number of moles of each reactant present and use this to show that copper (II) oxide was in excess. ii. The Copper (II) nitrate Solution was heated gently to concentrate it, and then left to crystalize. The mass of hydrated copper (II) nitrate crystal, Cu(NO 3 ) 2 -6H₂O, obtained was 2.52 g. Calculate the percentage fixed. 3. Organic compound Y contains Carbon, hydrogen, oxygen and nitrogen. 0.132 g of Y is burned completely in oxygen to produce 0.072 g of water, 0.176 g of carbon dioxide and 0.028 g of nitrogen. The molar mass of y is 132ng. mol -1 . Deduce to molecular formula for Y. Show how you arrived at your answer. [3]

[20 TOTAL MARKS] QUESTION SIX 1. A cook uses a microwave oven to heat a metal. The wavelength of the radiation is 1.20 cm. What is the energy of one photon of this microwave radiation? [1] 2. Calculate the energy required to excite the hydrogen atom from level n = 1 to level n = 2. Also calculate the wavelength of light that must be absorbed by a hydrogen atom in its ground state to reach this excited state. [2] 3. Predict the trend in radius for the following ions: 2 + ¿ 2 + ¿ ∧ S r ¿ 2 + ¿ ,C a ¿ 2 + ¿ , M g ¿ B e ¿ . Give reason for your trend. [5] 4. Complete the table [5] S No. n I Subshell name Possible m value Number of orbitals (a) 2 (b) 3 2s

(c) 5 1 (d) 4 4f 5. Using periodic table, write full, condensed electronic configuration, partial orbital diagrams showing valence electrons and number of inner electrons for the following elements. [7] (a) K (Z = 19) (b) Mo (Z = 42) [20 TOTAL MARKS]

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