CHE2122 — Chemistry¶
Bangladesh Open University — School of Science and Technology
B. Sc in Computer Science and Engineering Program — 2nd Year 1st Semester
General instruction (all terms): Answer any 5 (five) questions. The figures in the right margin indicate the full marks. All portions of each question must be answered sequentially.
Time: 3 hours | Total Marks: 5×14 = 70
161 Term (Jan – Jun 2016)¶
1.
(a) Describe the postulates of Bohr's theory of atom. 7
(b) What is ionization energies and electronegativity. 3
(c) Explain the periodicity of atomic volume and valency. 4
2.
(a) What are the conductors, insulators and semiconductors? 6
(b) Explain n-type and p-type semiconductors. 8
3.
(a) What is co-ordinate bond? Write the electronic formulae of the following compounds:
i) CO; ii) H₂O₂; iii) BF₃; iv) C₂H₄. 9
(b) Explain the following:
i) Ice floats on water;
ii) Water exists as a liquid under the ordinary conditions while H₂S exists as gas under the same conditions. 5
4.
(a) Define order of a reaction, molecularity of a reaction and half life period. 6
(b) Show that for first order reactions the half life period is independent of the initial concentration. 5
(c) The half-life of a substance in a first order reaction is 20 minutes. Calculate the rate constant. 3
5.
(a) Define carbonyl compound. How does acetaldehyde react with the following reagents?
i) CH₃MgI; ii) C₆H₆NHNH₂. 6
(b) Write a note on
i) Aldol condensation;
ii) Cannizzaro reaction;
iii) Nitration reaction;
iv) Friedel-Craft Alkylation. 8
6.
(a) What are exothermic and endothermic reactions? 4
(b) Explain the following terms:
i) Normality; ii) Molarity; iii) pH of Solutions. 6
(c) Calculate the molality of a sulfuric acid solution containing 24.4g of sulfuric acid in 198g of water. The molar mass of sulfuric acid is 98.08g. 4
7.
(a) What is reversible reactions and equilibrium constant? 4
(b) Establish a relationship between K_p and K_c. 6
(c) Write a short note on "Le Chatelier's Principle". 4
171 Term (2nd Year 1st Semester)¶
1.
(a) Define orbit and orbital. Are 2P, 3f and 4S³ orbital possible? Explain your answer. 3+5
(b) What is the maximum number of electrons that can be present in the principal level for which n=3? 6
2.
(a) What are semiconductors? How does semiconductivity arise? 2+6
(b) What do you mean by valance band, conduction band and forbidden band? 4
3.
(a) Define order and molecularity of a reaction. 5
(b) Derive the rate equation for first order reaction. 5
(c) The rate constant for a first order reaction is 1.54X10⁻³ Sec⁻¹. Calculate its half-life period. 4
4.
(a) Why chemical equilibrium is called a dynamic equilibrium? 6
(b) Derive the equilibrium constant (Kc) expression for the Schematic reaction
mM + nN ⇌ xX + yY 4
(c) State the laws of thermochemistry. 2+2
5.
(a) What are defects in solid/crystal? Write some importance of crystal defects. 2+2
(b) How many types of imperfections in crystalline solids? Give their names and explain point defects with suitable example. 3+3
(c) Show the hydrogen bonding in acetic acid molecules and find Isotope, Isobar, Isotone from the following atoms ¹⁴₆C, ³²₁₄Si, ¹²⁷₅₃I and ¹⁶₈O. 4
6.
(a) Define carbonyl compounds. How can you chemically distinguish between aldehyde and ketones? 1+4
(b) Explain the following terms
i) Markovnikov rule;
ii) Aldol condensation reaction;
iii) Halogenations reaction. 9
7.
(a) Write short notes on the followings
i) Noble gasses;
ii) Hydrogen bonding;
iii) Normality and pH of solutions;
iv) Diamagnetism and paramagnetism. 12
(b) Show how the P^H scale was established from 'onic product of water. 2
181 Term (2nd Year 1st Semester) Final Examination¶
1.
(a) What is an orbital? 3
(b) Write down the rules of ground state electron configuration of elements. 5
(c) Write the name of the orbital for which the quantum numbers are n = 2 and l = 1. 4
(d) Write the ground state electron configuration of element Na. 2
2.
(a) What is the rate of reaction? 3
(b) Describe the equation to calculate the rate constant of a 1st order reaction and show the half-life of a 1st order reaction is independent of initial concentration of reactants. 4+3
(c) Compared A decomposes to form B and C, the reaction is 1st order, A 25⁰C the rate constant for the reaction is 0.45s⁻¹. What is the half-life of A at 25⁰C? 4
3.
(a) What is ionization energy? Explain "ionization energy increases across a period. 2+4
(b) What are Nobel gases? What are their properties? 2+2
(c) Write the electronic formulae of the following compounds:
(i) C₂H₄; (ii) BF₃; (iii) PCl₅; (iv) H₂O₂. 4
4.
(a) Define valance band, conduction band and forbidden band? 5
(b) How many types of overlapping of covalent band are seen? 4
(c) Draw and explain the molecular orbitals of N₂ and O₂ according to MOT. 5
5.
(a) What are isotopes and isobars? Choose isotopes and isobars from the following list:
¹²₆C; ¹⁴₇N. 2+3
(b) What is equilibrium law? Establish the relation between K_P and K_C. 2+3
(c) The value of K_P at 20⁰C for the reaction 2NO(g) + Cl₂(g) ⇔ 2NOCl(g) is 1.9×10³ atm⁻¹. Calculate the value of K_C at the same temperature. 4
6.
(a) Explain the terms: (i) Normality; (ii) Molarity and (iii) Molality of a solution. 6
(b) Calculate the normality and molarity of a solution containing 20.7g of K₂CO₃ dissolved in 500ml of the given solution. 4
(c) What is meant by P^H? Calculate the P^H of 0.001N HCl assuming complete ionization of HCl. 1+3
7.
(a) What are alcohol and aldehyde compounds? 4
(b) Write down the following organic reaction:
(i) aldol reaction; (ii) cannizzaro reaction; (iii) haloform reaction (iv) Nitration reaction. 6
(c) Why does the electron affinity decrease down a group except flourine? 4
201 Term (2nd Year 1st Semester) Final Examination¶
1.
(a) Describe Rutherford's atomic model and mention its weakness. 6
(b) Write down postulates of Bhor's theory. 4
(c) Find out the number of orbital's for which the following sets of quantum numbers is possible n = 3, l =2 and m = (±2). 4
2.
(a) Write down the ground state electron configuration of following elements:
(i) C(6); (ii) S(16); (iii) Mo(42); (iv) Ni(28); (v) Na(11). 5
(b) Explain "electron affinity of an element decreases down a group". Why is the value of electron affinity for fluorine out of line? 2+3
(c) Why does the ionization energy of Na is lower than Li? 4
3.
(a) What are semiconductors? What types of defects are present in stoichiometric compounds? 2+3
(b) Draw and explain the molecular orbital's of O₂ according to MOT. 3
(c) Write the Lewis structure of the following molecules:
(i) H₂O; (ii) NH₃; (iii) C₂H₄; (iv) BeCl₂; (v) CO₂; (vi) HF. 6
4.
(a) Compare the properties of ionic and covalent compounds. 4
(b) Explain the following terms:
(i) Hydrogen bonding;
(ii) Metallic bonding;
(iii) Water has maximum density at 4⁰C. 3x2
(c) Draw the phase diagram of the water system and find the degrees of freedom in every region of this diagram. 4
5.
(a) What is equilibrium constant? Write down the characteristics of chemical equilibrium. 5
(b) Show the relation between K_e and K_p. 5
(c) Calculate the concentration of OH⁻ ions from water at 298K in 0.02M HCl solution. 4
6.
(a) Derive mathematical expression for the rate constant of a reaction (A→Products) of the first order. 4
(b) State and derive the Raoults law for dilute solution. 7
(c) 5.3 g of NaCO₃ is dissolved in 1 Kg of water. If the density of the solution is 0.997gml⁻¹. Calculate the morality and normality of the solution. 3
7.
(a) What are alcohol and aldehyde compounds? 3
(b) Write down the following organic reactions:
Aldol reaction, Cannizzaro reaction and Grignard reaction. 6
(c) How can you convert primary amide to primary amine? 2
(d) If a solution has a P^H of 5.50 at 25⁰C, calculate its [OH⁻]. 3
End of CHE2122 Chemistry compilation.