Solutions Warm-up 9 09-103 F 06

Solutions Warm-up 9 09-103 F 06 - 1 ) TRUE 6. Showing your...

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Solutions/Key Warm-up 9 (covering Sec. 3.6-3.8) DUE Tues. 10/3 09-103 Fall 2006 1. What does the atomic mass of 12.01 for the element carbon represent? ( 3) The weighted average ( 1) of the mass numbers (or masses) ( 1 ) of each of the naturally occurring isotopes for carbon ( 1 ). Grading Key 2. What is the value of Avogadro’s number? ( 1 ) errors Score 6.02 x 10 23 (of anything – atoms, molecules, people, etc.) 0-3 3 4-5 2.5 3. (a) How can you calculate the average mass of an individual atom? ( 2 ) 6 2 Element’s atomic mass (in g) ( 1 ) 7-8 1.5 6.02 x 10 23 ( 1 ) atoms 9 1 10 0.5 (b) Calculate the average mass of an individual magnesium atom. ( 3 ) 11 or more 0 24.31 g Mg ( 1 ) 6.02 x 10 23 atoms (1 ) = 4.04 x 10 -23 g / Mg atom ( 1 ) ( -1/2 if do not indicate grams) 4. For each mole of Al 2 O 3 molecules, how many moles of Al atoms and how many moles of O atoms are there? ( 2 ) Look at subscripts: 2 moles of Al atoms ( 1 ) and 3 moles of O atoms ( 1 ) 5. TRUE or FALSE? Molar mass is the mass of one mole of either an atom or a molecule. (
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Unformatted text preview: 1 ) TRUE 6. Showing your work clearly as on p. 141, calculate the molar mass of Al 2 O 3 . ( 7 ) 1 mol Al 2 O 3 = 2 mol Al + 3 mol O ( 2 ) = [ 2 mol Al (27.0 g Al / 1 mol Al) ] + [ 3 mol O (16.0 g O / 1 mol O) ] ( 1) (1 ) ( 1 ) ( 1 ) = 54.0 g Al + 48.0 g O = 102 g Al 2 O 3 ( 1 ) ( or in units of g/mol ) 7. TRUE or FALSE? The future effect of methane on Earths average temperature is predicted to be greater than that of CO 2 . ( 1 ) FALSE (It is predicted that methane will have less of an effect on raising Earths temperature). 8. TRUE or FALSE? O 3 in the stratosphere contributes to global warming. ( 1 ) FALSE (O 3 in the troposphere contributes to global warming.) 9. TRUE or FALSE? All greenhouse gases are assigned a Global Warming Potential value. ( 1 ) FALSE (Greenhouse gases with relatively short lifetimes and uneven distributions in the atmosphere are not assigned a GWP.)...
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This note was uploaded on 01/20/2012 for the course CHEMISTRY 103 taught by Professor Unknown during the Spring '08 term at Carnegie Mellon.

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