userdata-paziras-Chem101-Chap_03A

Massx noofxinformulaxatomicmassofx x100

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Unformatted text preview: ar Mass of PbSO4 : 1 mole Pb = 1 mole S = 4 moles O = 1 x 207.2 g = 1 x 32.07 g = 4 x 16.00 g = 207.2 g 32.07 g 64.00 g 303.3 g 303.3 g PbSO4 3 ? g PbSO4 = 6.30 moles PbSO4 x ¾¾¾¾¾¾¾ = 1.91 x 10 g PbSO4 1 molePbSO4 4 Chemistry 101 5. Chapter 3 Calculate the number of moles in 2.45 g of magnesium sulfate. Formula of magnesium sulfate: 2+ 2­ MgSO4 MgSO4 1 mole MgSO4 ? moles MgSO4 = 2.45 g MgSO4 x ¾¾¾¾¾¾¾ ????? g MgSO4 1 mole MgSO4 = Molar Mass of MgSO4 : 1 mole Mg = 1 mole S = 4 moles O = 1 x 24.31 g = 1 x 32.07 g = 4 x 16.00 g = 24.31 g 32.07 g 64.00 g 120.38 g 1 mole MgSO4 ? moles MgSO4 = 2.45 g MgSO4 x ¾¾¾¾¾¾¾ = 0.0204 moles MgSO4 120.38 g MgSO4 5 Chemistry 101 Chapter 3 PERCENT COMPOSITION · The percent composit ion of a compound is the mass percent of each element in the co mpound. Mass % X = no. of X in formula x atomic mass of X x 100 molecular mass of compound The recommended daily allowance of table salt (sodium chloride) is 2000. mg NaCl. How many mg of Na are contained in 2,000. mg NaCl? First Step: Calculate the mass of 1 mo le of co mpound 1 mo le Na 1 mo le Cl = = 1 x 22.9 g 1 x 35.45 g 1 mo le o f NaCl = = 22.99 g 35.45 g = 58.44 g Second Step: Calculate the % by mass o f each element in the compound % Na = 22.99 g x 100 = 39.34% 58.44 g % Cl = 35.45 g x 100 = 60.66% 58.44 g Third Step: Check if the percentages add up to 100% 39.34 % Na + 60.6...
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