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Catalyst – May 7-4, 2010. Monday Mystery Element f-block element Named for an 1801 asteroid Ceres Its oxide is used to coat walls of self-cleaning ovens. Catalyst – May 7-4, 2010. Monday Mystery Element f-block element Named for an 1801 asteroid Ceres
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Catalyst – May 7-4, 2010 Monday Mystery Element • f-block element • Named for an 1801 asteroid Ceres • Its oxide is used to coat walls of self-cleaning ovens
Catalyst – May 7-4, 2010 Monday Mystery Element • f-block element • Named for an 1801 asteroid Ceres • Its oxide is used to coat walls of self-cleaning ovens CERIUM!
Agenda • Mystery Element • Finish test from before spring break • On to the next one-molarity • Molality • Grams calculations • Exit Question
Solutions • Key Point #1: There are two main parts to a solution. The Solute : the substance dissolved in the solution The Solvent: the dissolving medium in the solution
Solutions Let’s consider an example: Solute: Solvent:
Solutions Let’s consider an example: Solute: Gatorade mix Solvent:
Solutions Let’s consider an example: Solute: Gatorade mix Solvent: Water
Solutions Solutions come in different concentrations, which we measure in molarity (M). M=
Solutions Solutions come in different concentrations, which we measure in molarity (M). M= Moles of solute Liters of solution * MUST BE IN MOLES OR LITERS, IF YOU HAVE MILLILITERS YOU MUST CONVERT! (COUGH, COUGH)
Example • What is the molarity of a solution that has 0.5 moles of lithium hydroxide (LiOH) dissolved in 1.0 L of water?
You do- whiteboards • What is the molarity of a solution that has 5 moles of barium bromide (BaBr2) dissolved in 2.0 L of solution?
Example • What is the molarity of a solution that has 0.25 moles of calcium sulfide (CaS) dissolved in 500 mL of solution? • WHAT DO YOU NOTICE???
You do- whiteboards • What is the molarity of a solution that has .88 moles of calcium oxide (CaO) dissolved in 300 mL of solution?
Example • How many grams of potassium chloride (KCl) are required to make 2.0 L of a 3.0 M solution? • WHAT DO YOU NOTICE? • EASY! Just convert moles to grams- you know how to do that!!
Molality Key Point #2: For chemists, molality expresses another form of concentration - similar to molarity. m = Moles of solute Kg of solvent It is the same thing, but instead of L on the bottom, it is kilograms on the bottom! Tomorrow!
Molality You mix 100 moles of HBr into 10 kg of Br, what is your molality?
Molality • If you mix together 15 mol of solute and 5 kg of solvent, what is your molality?
Rally-Coach- TEAMWORK!! • After this announcement, you will find 1 partner in the class. • One person will be writing ONLY what the coach tells them to write. If you think the coach is wrong, you can hint to them that its not. • One person will be coaching them through the problem. • After each problem, you switch roles! • If you finish, see me for extra credit.
Exit Question • How many grams of NaCl would it take make 2L of a 4M solution? • If you have 3.5 moles of NaCl in 2.2 L of water, what is the molarity?