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The lattice energy of LiF is 1023 kJ/mol, and the Li–F distance is 201 pm. MgO crystallizes in the same structure as LiF but with a Mg–O distance of 205 pm. Which of the following values most closely approximates the lattice energy of MgO: 256 kJ/mol, 512 kJ/mol, 1023 kJ/mol, 2046 kJ/mol, or 4008 kJ/mol? Explain your choice.
Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number for each. (a) the chalcogen with a mass number of 125 (b) the halogen whose longest-lived isotope is radioactive (c) the noble gas, used in lighting, with 10 electrons and 10 neutrons (d) the lightest alkali metal with three neutrons
Water gas, a mixture of and CO, is an important industrial fuel produced by the reaction of steam with red hot coke, essentially pure carbon: . (a) Assuming that coke has the same enthalpy of formation as graphite, calculate for this reaction. (b) Methanol, a liquid fuel that could possibly replace gasoline, can be prepared from water gas and additional hydrogen at high temperature and pressure in the presence of a suitable catalyst: . Under the conditions of the reaction, methanol forms as a gas. Calculate for this reaction and for the condensation of gaseous methanol to liquid methanol. (c) Calculate the heat of combustion of 1 mole of liquid methanol to and .
Calculate the molarity of each of the following solutions: (a) 293 g HCl in 666 mL of solution, a concentrated HCl solution (b) 2.026 g in 0.1250 L of a solution used as an unknown in general chemistry laboratories (c) 0.001 mg in 0.100 L, the maximum permissible concentration of cadmium in drinking water (d) 0.0079 g in one ounce (29.6 mL), the concentration of saccharin in a diet soft drink.
Outline the steps needed to solve the following problem, then do the calculations. Ether, , which was originally used as an anesthetic but has been replaced by safer and more effective medications, is prepared by the reaction of ethanol with sulfuric acid. What is the percent yield of ether if 1.17 L (d = 0.7134 g/mL) is isolated from the reaction of 1.500 L of (d = 0.7894 g/mL)?
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