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Week II Recitation problems

Week II Recitation problems - other isotope 3 Molecular...

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Recitation problems II (Anyone is free to suggest any discussion topics) 1. Avogadro’s number: number of molecules, Formula weights, atoms a. How many moles of atoms are there in 7.760 x 10 11 He atoms? b. How many atoms are there in 3.355 x 10 -4 moles of SF 6 molecules ? c. How many molecules are in 1.266 x 10 -3 mol of SO 2 molecules? d. How moles of AlCl 3 are in 4.1236 Formula units? 2. Atomic numbers, mass numbers a. How many neutrons do the following atoms have? Cl-35, U -235, C- 14, F-19 b. Strontium has four isotopes with the following masses and their relative abundances 83.9134 amu (0.56 %), 85.9094 amu (9.86%), 86.9089 amu (7.00%) and 87.9056 amu (82.58 %). Calculate the atomic mass of strontium. c. Naturally occurring silver (Ag) consist of two isotopes. One of the isotopes has a mass of 106.90509 amu and 51.84 % abundance. What is the atomic mass of the
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Unformatted text preview: other isotope? 3. Molecular weight and Stoichiometry calculations . a. Saccharin an artificial sweetener which has the composition 45.90 % C , 2.75 % H , 26.20% O, 17.50 % S and 7.65 % N. What is the empirical formula for saccharin? b. A gaseous mixture containing 4.15 mol of Hydrogen gas and 7.13 mol of Oxygen react to form steam (H 2 O). i) Write a balanced equation? ii) What is the limiting reagent? iii) What is the theoretical yield? iv) How many moles of excess reagent remain unreacted? c. Aluminum reacts with sulfur to form aluminum sulfide (Al 2 S 3 ). Initially 1.18 mol of Aluminum and 2.25 mol of sulfur are combined. i) Write a balanced equation? ii) What is the limiting reagent? iii) What is the theoretical yield? iv) How many moles of excess reagent remain unreacted?...
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