WS2_key - Chem 142 Name _ Worksheet 2: Atoms, Molecules and...

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Chem 142 Summer 2011 Page 1 of 3 Name ________________________________________ Section ________________ Worksheet 2: Atoms, Molecules and Ions 1. A 5.00g sample of magnesium phosphate contains 1.39g of magnesium. How much magnesium would a 1.00 kg sample contain? mass fraction = 1.39 g Mg 5.00 g sample = 0.278 Mg sample ( ) mass magnesium = 0.278 Mg sample ( ) ! 1.00 kg = 0.278 kg 2. What mass of sodium is in a 4.6g sample of sodium nitrate? M NaNO 3 = 22.990 + 14.001 + 3 ! 15.999 ( ) = 84.995 g mol mass fraction = 22.990 g Na 84.995 g sample = 0.271 Na sample ( ) mass sodium = 0.271 Na sample ( ) ! 4.6 g sample = 1.2 g Na 3. For each of the following statements, classify the statement as true or false and explain. a. Protons, neutrons and electrons all have approximately the same mass. False, electrons are 3 orders of magnitude smaller than protons and neutrons. b. Atoms with the same number of protons have identical chemical properties. True, the type of element is determined by the
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This note was uploaded on 01/19/2012 for the course CHEM 142A taught by Professor Campbell during the Summer '11 term at University of Washington.

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WS2_key - Chem 142 Name _ Worksheet 2: Atoms, Molecules and...

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