Unit 6 - Equilibrium Applications This is a continuation of the last unit (Equilibrium). Because many of the concepts here build on past material, you should be familiar with the last unit. For example, you should know how to a) set up an equilibrium law, b) solve equilibrium problems (using a RICE chart), c) use Le Chatelier’s principle, d) determine the charge on ions when an ionic solid dissolves in water. Background (3.3, 4.6) What is the molar mass of H 2 O? Molar mass is in units of g/mol. It is calculated from atomic weights. Molar mass of H 2 O = 2 x H + O = 2 x 1 + 16 = 18 g/mol. How many moles are in 18 g of NaCl? Factor label method: #mol = g x mol = 18 g x 1 mol = 0.3 mol (For NaCl, molar mass = 23 + 35.5) g 58.5 g How many g of CaCl 2 need to be added to 2 L of water to make a 3 M solution? First determine the number of moles required: #mol= 2L x 3mol/L = 6 mol. Next, convert mol to g using the molar mass of CaCl 2 (40.1 + 2 x 35.5 = 111.1 g/mol): #g = 6mol x 111.1g/mol = 667 g.
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