Class05

Class05 - Chemistry 83 Formation of Interstellar...

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Chemistry 83 Class05 1 Formation of Interstellar Substances-2 Molecular weight is the sum of atomic weights of all atoms represented by a formula Formula Sum of atomic weights Molecular Weight C 2 H 4 (molecular) 2(12) + 4(1) 28 CaBr 2 (empirical) 1(40) + 2(80) 200 Ca (empirical) 1(40) 40 C (diamond) (empirical) 1(12) 12 What is molecular weight?
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Chemistry 83 Class05 2 Mole is molecular weight expressed in grams and it is the mass of 6.02 x 10 23 molecules of a substance Formula Molecular Weight Mole Number of molecules C 2 H 4 (molecular) 28 28 g 6.0 x 10 23 CaBr 2 (empirical) 200 200 g 6.0 x 10 23 Ca (empirical) 40 40 g 6.0 x 10 23 C (empirical) 12 12 g 6.0 x 10 23 What is a “mole” in chemistry? Find the number of moles of CH 4 molecules in a 1.6 g sample of the substance. CH 4 ; 1(C) + 4(H); MW = 1(12) + 4(1) = 16; mole = 16 g; moles CH 4 = 1.6 g/16 g/mole = 0.10 mole Find the number of CH 4 molecules in a 1.6 g sample of the substance. moles CH
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This note was uploaded on 10/19/2011 for the course CHEM 83 taught by Professor Bonk,j during the Fall '08 term at Duke.

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Class05 - Chemistry 83 Formation of Interstellar...

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