CY 211 - Basic Inorganic Chemistry and Thermodynamics Past Paper PDF 20250729

CY 211 - Basic Inorganic Chemistry and Thermodynamics II Prof. K. Muralidharan School of Chemistry University of Hyderabad Basic Inorganic Chemistry  Basic Inorganic Chemistry 1. Nuclear Chemistry: Nuclear binding en...

CY 211 - Basic Inorganic Chemistry and Thermodynamics II Prof. K. Muralidharan School of Chemistry University of Hyderabad Basic Inorganic Chemistry  Basic Inorganic Chemistry 1. Nuclear Chemistry: Nuclear binding energy - Radioactivity - Artificial isotopes - Nuclear fission - Synthesis of trans - uranium elements - Separation of radioactive isotopes - Nuclear fusion - Application of isotopes - Radiocarbon dating [4 h] 2. Acids & Bases: Various definitions of acids and bases - Factors affecting strength of acids and bases - Ka, Kb, Kw and pH - Henderson’s equation -Hydrolysis of salts - Common ion effect - Brønsted and Lewis acids and bases - Gas phase versus solution phase acidity, HSAB principle -Surface acidity [6 h] 3. Non-aqueous Solvents: Properties of a solvent for functioning as an effective reaction medium - Types of solvents and general characteristics of liquid NH3, SO2, HF, H2SO4, BF3 and N2O4 - An introduction to superacids - Ionic liquids and supercritical fluids [5 h] 4. Chemistry of selected s- & p-block elements: Hydrogen bonds - Hydrates and water clathrates - Alkali metal solution in liquid ammonia - Complexation of alkali metals by crown ethers and cryptands - Alkali metal anions -Diborane – Structure and bonding - Noble gas compounds. [5 h] Suggested reading: 1. Catherine E. Housecroft and Alan G. Sharpe, Inorganic Chemistry, 2, & 4th Editions, Pearson Education Limited, 2005. 2. G. L. Miessler and D. A. Tarr, Inorganic Chemistry, 3rd Edition, Pearson Education, 2004. Thermodynamics II Gibbs and Helmholtz energy, chemical potential, free energy and entropy of mixing of ideal gas, ideal solutions, mixture of ideal solutions, colligative properties: boiling point, freezing point, solubility and osmosis (5h) Chemical equilibrium: Equilibrium constant of reaction of ideal gas and its temperature dependence: van’t Hoff equation, Le Chatelier principle, Fugacity and the Equilibrium Constant of real gas (3h). Phase equilibrium: Phase transitions of pure substances: phase stability, boundary and phase rule, examples of phase diagrams; thermodynamics of phase transition: Clausius-Clapeyron equation, order of phase transition; phase diagrams of binary systems, lever rule, liquid-liquid and solid-liquid phase diagrams (6h). Non-ideal solutions: Activity and activity coefficient, activity coefficient in concentration scales, activity of electrolyte, ionic activity and coefficient. (4h) (total: 18h) Suggested reading: 1. Physical Chemistry (6th edition) by Ira N. Levine 2. Physical Chemistry (3rd edition) by Gilbert Castellan 3. Physical Chemistry (3rd edition) by Thomas Engel & Philip Reid 4. Physical Chemistry (9th edition) by Peter Atkins and Julio de Paul  Origin of the Universe the most widely accepted theory for the origin and evolution of the universe to its present form is the “hot big bang”. It is supposed that all the matter in the universe was once contained in a primeval nucleus of immense density (~ 1096 g cm -3) and temperature (~1032 K). for some reason, it exploded and distributed radiation and matter uniformly throughout space. the universe is continually expanding and, on certain assumptions, extrapolation backwards in time indicates that the big bang occurred some 15 billion years ago. As the universe expanded it cooled; this allowed the four main types of force to become progressively differentiated, and permitted the formation of various types of particle to occur. One second after the big bang, after a period of extensive particle-antiparticle annihilation to form electromagnetic photons, the universe was populated by particles which sound familiar to chemists - protons, neutrons and electrons. Shortly thereafter, the strong nuclear force ensured that large numbers of protons and neutrons rapidly combined to form deuterium nuclei (p +n), then helium (2p + 2n). The process of element building had begun.  Fundamental particles of an atom An atom is the smallest unit quantity of an element that is capable of existence, either alone or in chemical combination with other atoms of the same or another element. The fundamental particles of which atoms are composed are the proton, electron and neutron. An atom consists of protons and neutrons, that make up the nucleus, and electrons that orbit the nucleus. The nucleus carries a positive charge; protons are positively charged, and neutrons don't carry a charge. The electrons, which carry a negative charge, move around the nucleus in clouds (or shells). The negative electrons are attracted to the positive nucleus by an electrical force. This attraction is what keeps the electrons orbiting the nucleus. https://www.cnsc-ccsn.gc.ca/eng/resources/radiation/atoms-nuclides-radioisotopes/  Atomic Weights The concept of “atomic weight” or “mean relative atomic mass” is fundamental to the development of chemistry. Dalton originally supposed that all atoms of a given element had the same unalterable weight but, after the discovery of isotopes earlier this century, this property was transferred to them. Today the possibility of variable isotopic composition of an element (whether natural or artificially induced) the possibility of defining the atomic weight of most elements as follows. an atomic weight of an element is “the ratio of the average mass per atom of an element to one-twelfth of the mass of an atom of 12C” It is important to stress that atomic weights (mean relative atomic masses) of the elements are dimensionless numbers (ratios) and therefore have no units.  Nuclide Isotopes A nuclide is a particular type of atom and possesses a Nuclides of the same element possess the same number characteristic atomic number, Z, which is equal to the of protons and electrons but may have different mass number of protons in the nucleus. Because the atom is numbers. The number of protons and electrons defines electrically neutral, Z also equals the number of electrons. the element but the number of neutrons may vary. A distinct kind of atom or nucleus characterized by a Nuclides of a particular element that differ in the number specific number of protons and neutrons of neutrons and, therefore, their mass number, are called isotopes. Isotopes of some elements occur naturally while Nuclides (X) are the nuclei of atoms of a specific isotope. others may be produced artificially. They are characterized by the number of positively charged protons (Z), neutrons (N) and the energy state of Elements that occur naturally with only one nuclide are the nucleus. monotopic and include phosphorus, 31 19 15𝑃, and fluorine 9𝐹 The mass number, A, of a nuclide is the number of protons Elements that exist as mixtures of isotopes include C ( 126C and neutrons in the nucleus. and 136C) and O ( 168O, 178O and 188O).  These values represent the energy released per nucleon upon the formation of the nucleus from its fundamental particles. It give a measure of the relative stabilities of nuclei with respect to decomposition into those particles. The nucleus with the greatest binding energy is 56 26𝐹𝑒 and this is therefore the most stable nucleus. In general, nuclei with mass numbers around 60 have the highest average binding energies per nucleon, and it is these elements (e.g. Fe, Ni) that are believed to constitute the bulk of the Earth’s core. Nuclei with mass numbers of 4, 12 and 16 have relatively high binding energies per nucleon, implying particular stabilities 4 12 16 Fig. Variation in average binding energy per nucleon as a function associated with 2He, 6𝐶and 8O. of mass number. Note that the energy scale is positive, meaning that the nuclei with the highest values of the binding energies These nuclei tend to be those used as projectiles in the release the greatest amount of energy upon formation. synthesis of the heaviest nuclei. Finally, the binding energy per nucleon decreases appreciably for mass numbers >100. Atoms are stable when the number of neutrons and protons in the nucleus are balanced. When there is a significant imbalance between the number of neutrons and protons in a nucleus, the atom becomes unstable and in order to achieve stability, the atom may undergo a transformation or radioactive decay. The data in Figure are of crucial significance for the application of nuclear reactions as energy sources. A reaction involving nuclei will be exothermic if: ❑ heavy nucleus is divided into two nuclei of medium mass (so-called nuclear fission). or ❑ two light nuclei are combined to give one nucleus of medium mass (so-called nuclear fusion).  Radioactivity Nuclear emissions When one nuclide decomposes to form a different nuclide, it is said to be radioactive. In such nuclear changes, three types of emission were initially recognized by Rutherford: -particles (now known to be helium nuclei, [ 42He]2+); -particles (electrons emitted from the nucleus and having high kinetic energies); -radiation (high-energy X-rays). An example of spontaneous radioactive decay is that of carbon-14, which takes place by loss of a -particle to give nitrogen-14 and this decay is the basis of radiocarbon dating More recent work has shown that the decay of some nuclei involves the emission of three other types of particle: the positron (β+ ); the neutrino (𝑒 ); the antineutrino. A positron is of equal mass but opposite charge to an electron. A neutrino and antineutrino possess near zero masses, are uncharged and accompany the emission from the nucleus of a positron and an electron respectively.  Nuclear Stability and radioactivity A nucleus is stable if it cannot be transformed into another configuration without adding energy from the outside. Of the thousands of nuclides that exist, about 250 are stable. A plot of the number of neutrons versus the number of protons for stable nuclei reveals that the stable isotopes fall into a narrow band. This region is known as the band of stability (also called the belt, zone, or valley of stability). The straight line in the graph below represents nuclei that have a 1:1 ratio of protons to neutrons (n:p ratio). The nuclei that are to the left or to the right of the band of stability are unstable and exhibit radioactivity. They change spontaneously (decay) into other nuclei that are either in, or closer to, the band of stability. These nuclear decay reactions convert one unstable isotope (or radioisotope) into another, more stable, isotope. Note that the lighter stable nuclei, in general, have equal numbers of protons and neutrons. For example, nitrogen-14 has seven protons and seven neutrons. Heavier stable nuclei, however, have increasingly more neutrons than protons. For example: iron-56 has 30 neutrons and 26 protons, an n:p ratio of 1.15, whereas the stable nuclide lead-207 has 125 neutrons and 82 protons, an n:p ratio equal to 1.52. This is because larger nuclei have more proton-proton repulsions, and require larger numbers of neutrons to provide compensating strong forces to overcome these electrostatic repulsions and hold the nucleus together. https://openstax.org/books/chemistry-atoms-first-2e/pages/20-introduction Several observations may be made regarding the relationship between the stability of a nucleus and its structure. Nuclei with even numbers of protons, neutrons, or both are more likely to be stable. Nuclei with certain numbers of nucleons, known as magic numbers, are stable against nuclear decay. These numbers of protons or neutrons (2, 8, 20, 28, 50, 82, and 126) make complete shells in the nucleus. These are similar in concept to the stable electron shells observed for the noble gases. Nuclei that have magic numbers of both protons and neutrons, such as 2He4, 8O16, 20Ca40, and 82Pb208, are called “double magic” and are particularly stable. These trends in nuclear stability may be rationalized by considering a quantum mechanical model of nuclear energy states analogous to that used to describe electronic states earlier in this textbook. Principle of physical chemistry, B.R. Puri, L.R. Sharma and Madan S. Pathania https://openstax.org/books/chemistry-atoms-first-2e/pages/20-introduction  Beta decay modes A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay. There are two forms of beta decay, β − decay and β+ decay, which produce electrons and positrons respectively. β− decay (electron emission) An unstable atomic nucleus with an excess of neutrons may undergo β− decay, where a neutron is converted into a proton, an electron, and an electron antineutrino (the antiparticle of the neutrino): n → p + e − + νe β− decay commonly occurs among the neutron-rich fission byproducts produced in nuclear reactors. Free neutrons also decay via this process. β+ decay (positron emission) Unstable atomic nuclei with an excess of protons may undergo β+ decay, also called positron decay, where a proton is converted into a neutron, a positron, and an electron neutrino: n → p + e + + νe β+ decay can only happen inside nuclei when the absolute value of the binding energy of the daughter nucleus is greater than that of the parent nucleus, i.e., the daughter nucleus is a lower-energy state. https://en.wikipedia.org/wiki/Beta_particle  Particle Energy range   6-16  10−13 J   0.03–5.0  10−13 J   10-8 J -Radiation has a very short wavelength and very high energy. Its emission often accompanies the loss of - or -particles. This phenomenon arises because the daughter nuclide (the product of - or -particle loss) is often in an excited state, and energy in the form of -radiation is emitted as the transition from excited to ground state occurs. The energies of -radiations are in the same range as those of b-particles, but their penetrating power is far greater; a Pb shield (several centimetres thick) is required to absorb -radiation  Nuclear transformations Since the loss of a  particle is accompanied by a one-unit increase in atomic number and a retention in mass number, it effectively converts a neutron into a proton. Since an a-particle is a helium nucleus (i.e. [ 42He2+ ]), its emission lowers the atomic number by two and the mass number by 4. The loss of the a-particle is accompanied by emission of -radiation, but the latter affects neither the atomic nor mass number. The -particle in equation is shown as neutral helium gas; as they are emitted, -particles readily pick up electrons from the environment Nuclear transformations through decay Radioactive series Radioactive displacement law loss of a accompanied by Shifted to particle  Two-unit decrease in The daughter element is atomic number therefore two places to the Four-unit decrease in left of the parent in the mass number periodic table  One-unit increase in The daughter element is one atomic number place to the right of the No change in mass parent element in the number periodic table  k = first order rate constant Or Disintegration constant or decay constant The rate of an ordinary chemical reaction depends on temperature (the Arrhenius equation relates the rate constant, k, to the temperature, T, in kelvin). However, radioactive decay is temperature-independent.  Fig. 2.4 Radioactive decay follows first order kinetics and a plot of the number of nuclides against time is an exponential decay curve. The graph shows a decay curve for radon-222, which has a half-life of 3.82 d Figure 2.4 shows the first order decay of 222 86Rn, and the exponential curve is typical of any radioactive decay process. A characteristic feature is that the time taken for the number of nuclides present at time t, Nt, to decrease to half their 𝑁 number, 2𝑡 is constant. This time period is called the halflife, 𝑡1Τ2 of the nuclide. The half-life of a radioactive nuclide is the time taken for the number 𝑵 of nuclides present at time t, Nt, to fall to half of its value, 𝟐𝒕  The rate of an ordinary chemical reaction depends on temperature (the Arrhenius equation relates the rate constant, k, to the temperature, T, in kelvin). However, radioactive decay is temperature-independent.  Artificial isotopes Bombardment of nuclei by high-energy a-particles and neutrons Similar to naturally occurring radioactive processes, transformations occur when nuclei are bombarded with high-energy neutrons or positively charged particles. The neutrons are effective since, being uncharged, they are not subject to electrostatic repulsion by nuclei. Such nuclear reactions take place with conservation of atomic number and mass number and provide a means of generating artificial isotopes. 30 The nuclear transformation may also be written using the notation 27 13Al(α,n) 15P which has the general form shown in equation 2.10 Equation 2.9 shows the reaction that occurs when an Al foil is bombarded with a-particles which have been given high energies in a cyclotron (an accelerating machine).  Artificial isotopes Bombardment of nuclei by high-energy a-particles and neutrons The product of reaction 2.9 rapidly decays (t1/2 = 3:2 min) according to equation 2.11. The loss of a positron from the nucleus effectively converts a proton into a neutron. High-energy (or ‘fast’) neutrons are produced by the nuclear fission of 235 92U and have energies of 1MeV. The bombardment of sulfur-32 with fast neutrons (equation 2.12) gives an artificial isotope of phosphorus, but 32 15P has a half- life of 14.3 days and decays by -particle emission (equation 2.13).  Bombardment of nuclei by ‘slow’ neutrons An important process for the production of artificial radioactive isotopes is the (n, ) reaction which is brought about by the bombardment of nuclei with ‘slow’ or thermal neutrons. The neutrons are formed by fission of 23592U nuclei and their kinetic energy is reduced by elastic collisions with low atomic number nuclei (e.g. 126C or 21H) during passage through graphite or deuterium oxide (heavy water). A thermal neutron has an energy of  0.05 eV. In reaction 2.14, naturally occurring phosphorus-31 (the target nucleus) is converted into artificial phosphorus-32. The production of artificial nuclides has two important consequences: the production of artificial isotopes of elements that do not possess naturally occurring radioisotopes; the synthesis of the transuranium elements, nearly all of which are exclusively man-made. The transuranium elements (Z 93) are almost exclusively all man-made. Other man-made elements include technetium (Tc), promethium (Pm), astatine (At) and francium (Fr).  Nuclear fission The action of thermal neutrons on 235 92U results in a reaction of the general type shown in equation 2.15 where the fission process is variable; Reaction 2.16 gives a typical example; once formed, yttrium-95 and iodine-138 decay by b-particle emission with half-lives of 10.3 min and 6.5 s respectively. The reaction must proceed with conservation of mass number and of charge. The mass numbers are denoted by the superscripts, and the charges by the subscripts (i.e. the number of protons). A particular reaction path during nuclear fission is called a reaction channel, and the yields of different nuclei in the fission of 235 92U indicate that it is more favourable to form two isotopes lying in the approximate mass ranges 100 to 90 and 134 to 144, than two nuclides with masses 144, or >100 and