Name __________________________ Geochemistry Fall 2005Chemistry refresher — Due Sept. 7th(and kick-start for the semester)Attach separate sheets showing all of your work if necessaryPractice chemistry skills using ExcelFaure Ch. 4, problem 1: Recalculate the chemical composition of pyrolite (Table 4.2, column 1 — seebelow) in terms of the weight percent concentrations of the elements and rank them in terms of theirabundance.Composition(%)SiO245.2MgO37.5FeO8.0Al2O33.5CaO3.1Na2O0.57Cr2O30.43MnO0.14P2O50.06K2O0.13TiO20.17Sum98.8Balancing equationsTry these examples:1) SiO2 + HF Æ SiF4 + H2O2) Fe2O3 + CO Æ Fe + CO2Atomic weights and formula weights3) Calculate the atomic weight of oxygen given the abundances and masses of its three naturallyoccurring stable isotopes:Isotope of oxygenAbundance(%)Mass(amu)Oxygen-1699.75715.99491463Oxygen-170.03816.9991312Oxygen-180.20517.9991603Answer: 15.9994 (from your periodic table)Name __________________________ Geochemistry Fall 20054) Calculate the formula weight of albite (NaAlSi3O8) using the atomic weights in your periodic table orin Table 6.2 of your text. (Answer: 262.223 amu)Moles5) How many moles are in 24.022 g of C?6) What is the mass of 5 moles of Na?7) How many moles of Na+ are present in one liter of an aqueous solution of Na2SO4 containing 4.760 gof the compound? (Answer: 0.06702 moles)8) What is the weight of one atom of strontium-86 in grams given that the mass of this isotope is85.909262 amu?9) One atom of uranium-238 weighs 3.953 x 10-22 g. Does your answer to Question 8 make sense basedon this information? Why?10) How many atoms of iron are present in 7.00 g of pyrite (FeS2)? (Answer: 3.5134 x 10-22 atoms)11) What is the concentration of Al in the mineral kyanite (Al2SiO5)? (Answer: 33.3%)12) If the concentration of SO4 is 2.5 x 10-3 mol/L, how many grams of SO4 are present in one liter?(Answer: 0.240
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