ch.  6 & 9  mole & stochiometry                       test                          55 points                               chemistry

In problems involving any calculation, show your work in an organized manner, include (i) any relevant equation (or formula), (ii) conversion factor(s), (iii) put the proper units in your calculations and answer, and (iv) have the proper number of significant figures in your answer.


1.  Solve.  [15 points]

a.  6.0 kg water =  __ mole

b.  35 millimole of carbon dioxide = __  g of carbon dioxide

c. 88 trillion calcium chloride molecules  =  __ moles of calcium chloride

2. Fill-in the blank, where the % yield is 85 %.  [20 points]

Excess Na3PO4  +  5.0 g Ca(NO3)2  →    ___ g Ca3(PO4)2  +  NaNO3

3.  The complete combustion of 2.0 g of a chemical with carbon, hydrogen, and oxygen generates 3.826 g of carbon dioxide and 2.348 g of water.  What is the chemical’s empirical formula ?  [20 points]