Physical Chemistry

2. Hydrogen iodide gas decomposes into hydrogen gas and iodine gas according to the equation below. A 2.25 L container containing this equilibrium system is analyzed and found to contain 2.34 moles of hydrogen iodine and 1.76 moles of hydrogen gas. If Keq for the reaction is 2.86 x 10², what concentration of iodine gas is present in the system? (2 marks) Bonus: what amount of iodine gas is present in the system? (1 mark) 2 HI(g) → H₂(g) + 12 (8)

Problem 1: (2 Mark) What is the physics information that can be obtained from the target by using the X- ray technique either throughout the result obtained directly form the X-ray or by farther calculation?

Problem 2: (2 Mark) (a) In a diffractometer experiment a specimen of thorium (Th) is irradiated with tungsten radiation of λ= 1.476 x 10-¹0 m. Calculate the angle, 0, of the 4th reflection which is 311? Hint: Atomic volume of thorium is 19.9 cm³/mol. (1 Mark) (b) Suppose that the experiment described in part (a) is repeated but this time the incident beam consists of neutrons instead of x-rays. What must the neutron velocity be in order to produce reflections at the same angles as those produced by x-rays in part (a)? (1 Mark)

Problem 3: (2 Mark) A Debye-Scherrer powder diffraction experiment using incident copper (Cu) radiation gave the following set of reflections expressed as 2 Ka 0:38.40°; 44.50°; 64.85°; 77.90°; 81.85°; 98.40°; 111.20°. (a) Determine the crystal structure. (0.5 Mark) (b) Calculate the lattice constant, a. (0.5 Mark) (c) Assume that the crystal is a pure metal and based on the hard-sphere approximation calculate the atomic radius. (0.5 Mark) (d) Calculate the density of this element which has an atomic weight of 66.6 g/mol. (0.5 Mark)

Problem 4: (2 Mark) The following diffractometer data (expressed as 20) were generated from a specimen irradiated with silver (Ag) Ka radiation: 14.10°; 19.98°; 24.57°; 28.41°; 31.85°; 34.98°; 37.89°; 40.61⁰. (a) Determine the crystal structure. (0.5 Mark) (b) Calculate the lattice constant, a. (0.5 Mark) (c) Assume that the crystal is a pure metal and on the basis of the hard-sphere approximation calculate the atomic radius. (0.5 Mark) (d) At what angle would we find the first reflection if, instead of K radiation, we used silver L radiation to illuminate the specimen? (0.5 Mark)

Problem 5: (2 Mark) What acceleration potential V must be applied to electrons to cause electron diffraction on (220) planes of gold (Au) at 8 = 5°?

Question 2 a. Using sketches explain the differences between a) an Open system; b) a closed system and c) an isolated system and d) Surrounding b. Nitroglycerine is an explosive that forms four different gases on 2C3H5(NO2)3 = 3N2(g)+ 0.5 O2(g) +6CO2(g) + 5H₂O(g) detonation. Calculate the enthalpy change when 10g of nitroglycerine is detonated. The enthalpy of formation of nitroglycerine, Hᵒ(t), is -346kJ/mol. Obtain heat capacity values from any text. Need mol mass of NTG?

Question 1 a). Calculate the minimum amount of ice at 0°C that must be added to 350mL of diet cola to cool it from 20.5°C to 0°C. Assume that the specific heat capacity and density of diet cola are the same as for water and that no heat is gained or lost to the surroundings. The heat of fusion of water is 333J/g, the specific heat capacity of water is 4.182J/g.K b) Using examples, explain the meaning of an intensive variable or property i. a thermodynamic state function ii. an extensive variable or property

Problems 1. The following electrode potentials were observed after a 1-year immersion period in natural seawater of pH 8.0 [20]:

Question 3 Using the letters/symbols for Entropy, Enthalpy and Gibbs free energy only (S, H, G), state a. the condition/s for a spontaneous reaction (spontaneity) b. Reversibility c. Irreversibility d. Explain the various ways in which a system may 'disperse' energy