# Is aging primarily an example of a physical or chemical change? Explain.

a: Explain the process of fading of a carpet upon repeated exposure to sunlight? Is the reaction chemical or a physical change? 1b. Is aging primarily an example of a physical or chemical change? Explain. 1c) Which are closer together: the two nuclei within molecular fluorine (F2) or the two nuclei within potassium fluoride (KF)? 2a: Which has greater potential energy and why: an electron in a 3s orbital or an electron in a 3p orbital? 2b: Which experiences a greater effective nuclear charge, an electron in the outermost occupied shell of argon or one in the outermost occupied shell of potassium? So which is bigger and why? 2c: The molecular geometry of water is tetrahedral, but its shape is bent. Why? 3a) Is this equation balanced? Explain your answer. 4C6H7N5O16(s) + 19O2(g) 24CO2(g) + 20NO2(g) + 14H2O(g) 3b) For the reaction below, use the bond energies to calculate the net energy of reaction and state if reaction is exothermic or endothermic reaction with reason(s). 2N N + 2O = O (N N is +946 Kj/mole; 2N = O + 2N = O O = O is +498 Kj/mole; N = O is – 631 Kj/mole). 4b: When the pH of a solution is 2, the concentration of hydronium ions is 1 10-2 M = 0.01 M. Assume that the volume of this initial solution is 500 ml and that the solution is not buffered. What is the pH after an additional 200 ml of pure water is added to the initial solution? Is this solution acidic or basic? (Note you will need a calculator with a logarithm function). 2
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