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New York State Chemistry Regents June 2008
Chemistry Regents June 2008 - Question 56 PDF Print E-mail
Written by The Chemistry Wizard   

chemjun08q (56).

Moles = grams/ molar mass

20 grams/ 85 (g/mol) = .235 moles

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Last Updated on Wednesday, 04 March 2009 05:03
 
Chemistry Regents June 2008 - Question 35 PDF Print E-mail
Written by The Chemistry Wizard   

chemjun08q (35)
(4) 4% is the correct answer.

In order to calculate the density of aluminum, you need to divide mass by volume.  In this case 25.6/9.1 = 2.81.  If we look at Table S, we see that the density of Aluminum is 2.698.  In order to calculate percent error, we first substract:  2.81-2.698= .112.  Then we divide: .112/2.81 = .039 – or 4%.

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