180 likes | 311 Views
Tonight ’ s Homework. skim ch 11.2 (373 – 377) p 393, # 60 – 64, 67. Stoichiometry – ch 11. A cupcake analogy. 5 eggs + 1 box cake mix 18 cupcakes. +. . What do I need to make 36 cupcakes…. 10 eggs + 2 boxes cake mix 36 cupcakes. +. .
E N D
Tonight’s Homework • skim ch 11.2 (373 – 377) • p 393, # 60 – 64, 67
A cupcake analogy 5 eggs + 1 box cake mix 18 cupcakes +
What do I need to make 36 cupcakes… 10 eggs + 2 boxes cake mix 36 cupcakes +
How many cupcakes can I make if I have 1 dozen eggs and 2 boxes mix? 12 eggs + 2 boxes cake mix 36 cupcakes + +
How many cupcakes can I make if I have 1 dozen eggs and 3 boxes mix? 12 eggs + 3 boxes cake mix 36 cupcakes + + +
What if I started with 300 g eggs and 90 g cake mix? Convert to a unit that can be used to compare the two… Chemists use MOLES!!!
Stoichiometry • Big Idea: The amount of each reactant present determines how much product can form. • stoichiometry: the study of quantitative relationships between the amounts of reactants used and amounts of products formed in a chemical reaction.
Stoichiometric Calculations section 11.2
Mass Production (an analogy ) • 2-L bottles of soda • 100,000 bottles per order • Best case scenario, how many liters of soda should be “batched” at a time? • 200,000 L
Thinking like a chemist… • “Balanced Chemical Equation” • Mole Ratio • Conversion
The basics of stoichiometric conversions… • Best Case Scenario = Balanced Chemical Eqn. • The mole ratio is the missing link between the best case scenario (balanced chemical equation in moles) and reality (in grams). • DETERMINE mole ration FROM THE BALANCED EQUATION • 3 types of conversions • mole to mole • mole to mass • mass to mass • Use molar mass (MM) to convert between moles and mass. For all of them, GO TO MOLES FIRST!
3 groups – 3 reactions • http://commons.wikimedia.org/wiki/File:Potassium_water_20.theora.ogv or • https://www.youtube.com/watch?v=oqMN3y8k9So • http://www.teachertube.com/viewVideo.php?video_id=67110 or • https://www.youtube.com/watch?v=Mx5JJWI2aaw • http://teachertube.com/viewVideo.php?video_id=122767&title=WHOOSH______Bottle&vpkey=&album_id= • https://www.youtube.com/watch?v=x2BXuI52fOI
3 groups – 3 problems • Determine what type of conversion • mole to mole • mole to mass • mass to mass • Work through the problem to solve it. • Outline the steps to solve this type of problem. • Be prepared to teach it to your classmates.
Groups 1 & 2 • Potassium metal reacts vigorously with water to produce potassium hydroxide and hydrogen gas. If 0.0400 moles of potassium is used, how many moles of hydrogen gas is created?
Groups 3 & 4 • Determine the mass of sodium chloride (NaCl) commonly called table salt, produced when 1.25 moles of chlorine gas (Cl2) reacts vigorously with excess sodium.
Groups 5 & 6 • Gasohol is a mixture of gasoline and ethanol. Determine the mass of CO2 produced from the combustion of 100.0 g ethanol (C2H5OH).