CHE - 1
Atoms and Molecules
(Tutor Marked Assignment)
Maximum Marks: 100
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- a) Describe the common features which can be explained by the theoretical model of Bohr? Briefly write the limitation of this model.
- b) Calculate the ionization energy of hydrogen atom using Bohr’s theory.
- a) Ans -
- 2. a) Derive an expression for calculating energy values corresponding n = 3 for a particle in one dimensional box.
- b) Write the values of four quantum numbers for 3d
- a) Ans -
- b) Ans -
- a) Explain the reason for the variation of the first ionization energies of the third period elements.
- b) Calculate the lattice energy (in Units kJ mol1) for ZnO crystal using Eq. 3.4 based on electrostatic model and using a Born-Haber cycle. Compare the two answers and comment on any difference.
- a) Ans
- b) ANS-For the theoretical calculation using the Born-Landé equation:
- a) In carbonate ion, all the three CO bonds have identical bond length. Explain.
- b) Explain the type of hybridization in phosphorous pentafluoride
- a) Ans-
- a) By writing molecular orbital configuration for each of following molecules calculate the bond order and also determine whether it is paramagnetic or diamagnetic.
(i) NO (ii) O2
- b) Using suitable examples define gerade and ungerade orbitals.
- a) Ans-i)The MO diagram for NO is as follows
(The original was this; I added the orbital depictions and symmetry labels.)
- b) Ans- Orbitals which are left unchanged by the operation of inversion (are symmetric) are labelled with a subscript g, while those which undergo a change in sign (are antisymmetric) are labelled u. The symbols g and u come from the German words "gerade" and "ungerade" meaning "even" and "odd" respectively.
If inversion through the center of symmetry in a molecule results in the same phases for the molecular orbital, then the MO is said to have gerade (g) symmetry, from the German word for even. If inversion through the center of symmetry in a molecule results in a phase change for the molecular orbital, then the MO is said to have ungerade (u) symmetry, from the German word for odd.
- a) The dipole moment of HBr is 2.60 1030 C m and interatomic distance 141 pm. What is the percentage ionic character of HBr?
- b) Draw all of the stereoisomers of 2,3-butandiol, label meso compounds and pairs of enantiomer.
- c) What is the predicted magnetic moment of Cu+ and Cu2+ ions in B Unit (Atomic number of Cu 29)?
- a) Given that the spacing of the lines in the microwave spectrum of 24Al1H is constant at 12.604 cm1. Calculate the moment of inertia and bond length of the molecule
- b) Determine the wavelength for a transition from the = 0 to the = 1 level. Is this transition in the IR region of the electromagnetic spectrum?
- c) Which of the following molecules exhibit rotational and or vibrational spectra
H2, HF, CO, NO
- a) From the infrared spectrum given below, identify the possible functional groups corresponding to the peaks indicated in the arrows.
Ans-WATCH BOOK .IMPOSSIBLE TO WRITE ON PDF FORMAT
- b) Explain why *transitions are the most useful transition in UVVIS spectroscopy? (3)
- c) UVVIS absorption spectra are broad band spectra. Explain
- Normal water contains isotope of hydrogen 3H, tritium. It has a half-life of 12.3 years. Determine the age of a bottle of wine whose 3H radiations is about 1/10 that present in new wine.
- a) Arrive at the Lewis structure of XeF4 using the steps given in Unit 3. (4)
- b) Predict the hybridization state of each carbon atom in allene which has the following structure:
CH2 = C = CH2
- c) Calculate the number of normal modes of vibration for the following compounds:
- i) H2O
- ii) HBr
- b) Ans-Geometry