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announcements. WebStudies test and Tutorial Tut Test 5 (formative assessment): Friday, 12 th 12:00 → Tuesday, 16 th 18:00 Tutorial 6: Thursday 18 th 14:00. reading assignment: chapter 2 videos WebStudies. the mole defining the mole molar mass amount-mass-number conversions
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announcements WebStudies test and Tutorial Tut Test 5 (formative assessment):Friday, 12th 12:00 → Tuesday, 16th 18:00 Tutorial 6: Thursday 18th 14:00
reading assignment: chapter 2 videos WebStudies the mole defining the mole molar mass amount-mass-number conversions mass percentage determine formula of unknown compound empirical/molecular formulas writing & balancing chemical equations calculating quantities (stoichiometry) mole-mole conversions from equations limiting reactants reaction yields fundamentals: solution stoichiometry molarity amount-mass-number conversions diluting molar solutions reactions in solution
peer-assisted group learning (PAGL) interactive –style teachingenquiry based learning learning opportunities prepare for contact session: you do assigned readingyou watch video clips Blackboard you work related sample problems text book/web you reflect: wonder, think about the concepts during contact session: we ask & test understanding of concepts we put up questions and discuss the content your group discusses/decides a response your scribe (guy in the middle) communicates your group compares group behind/front no-one calls answers, chews, misbehaves, etc.
this lecture the mole defining the mole molar mass amount-mass-number conversions mass percent determine formula of unknown compound empirical/molecular formulas writing & balancing chemical equations calculating quantities (stoichiometry) mole-mole conversions from equations limiting reactants reaction yields fundamentals: solution stoichiometry molarity amount-mass-number conversions diluting molar solutions reactions in solution
limiting reactants You make sandwiches that contain exactly 2 slices of bread and 1 slice of ham. If you have 23 slices of ham and 50 slices of bread, how many sandwiches can you make? 2 slices bread + 1 ham → 1 sandwich (theory) 50 slices 23 slices (given amounts) 2.17 bread 1 ham 50 bread 23 ham 2 bread 1 ham given theory a) compare 50 25 b) bread:ham ratio given c) 23 bread more than needed none of the above d)
limiting reactants You want to make sandwiches that specifically contain 2 slices of bread, 1 slice of ham and 3 slices of pickles. How many sandwiches can you make if you have 31 slices of bread, 17 slices of ham and 42 slices of pickles? theory limiting 2 bread + 1 ham + 3 pickles → 1 sandwich given amounts 31 17 42 = 15.5 sandwich 31 bread × a) 14 1 sandwich1 ham 1 sandwich3 pickles 1 sandwich2 bread = 17 17 ham × 15 b) = 14 42 pickles × c) 17 none of the above d)
limiting reactants Consider the reaction stated below. If you reacted 4 moles of N2 and 6 moles of H2, which is the limiting reactant? a) N2 b) H2 c) NH3 d) none of the above N2(g) + 3 H2(g) → 2 NH3(g) (theory) b) stoichiometry: 1.5 mol H2 1 mol N2 3 mol H2 1 mol N2 (theory) a) limiting 6 mol H2 4 mol N2 b) given: = c) (given) d)
limiting reactants A reaction vessel contains 6 moles of N2 and 4 moles of H2 that reacts according to the reaction stated below. Which is the limiting reactant? limiting N2 + 3 H2→ 2 NH3 NH3 (mol): = 12 mol NH3 limiting NH3 (mol): = 2.7 mol NH3 OR a) N2 0.6 H2 1 N2 4 H2 6 N2 3 H2 1 N2 H2 b) given theory given c) NH3
limiting reactants Consider the reaction stated below. If you had 4 moles of N2 and 6 moles of H2, what is the maximum amount of NH3 one could produce in this reaction? a) 8 moles NH3 b) 4 moles NH3 c) 12 moles NH3 d) 6 moles NH3 N2(g) + 3 H2(g) → 2 NH3(g) b) a) NH3 (mol): = 4 mol NH3 b) NH3 (mol): = 8 mol NH3 c) d) e)
limiting reactants Examine the molecular view of the reaction between AB and B2 in the gas phase: The correct statement about this reaction is: a) a) The balanced equation: AB + B2 → AB3 b) AB and B2 are initially in stoichiometric amounts c) AB is the limiting reactant d) The product of the reaction is A2B b) c) c) d) balanced equation: 2 AB + B2→2 AB2 e) Asirvatham, 2010
Identify whether this presentation represents the combustion of methane (CH4) with a) stoichiometric amount of oxygen b) methane limiting c) oxygen limiting c) c) excess limiting CH4 + 2 O2 → CO2 + 2 H2O 2 mole O2 5 mol CH4 2 mole O2 1 mol CH4 2 1 want stoichiometry: = a) 0.4 1 have b) b) given: = c) c) c) Wood, 2006
Identify whether this presentation represents the combustion of methane (CH4) with a) stoichiometric amount of oxygen b) methane limiting c) oxygen limiting b) limiting excess CH4 + 2 O2 → CO2 + 2 H2O 2 mole O2 1 mol CH4 7 mole O2 2 mol CH4 2 1 stoichiometry: = want a) 3.5 1 have given: = b) b) c) c) c) Wood, 2006
Identify whether this presentation represents the combustion of methane (CH4) with a) stoichiometric amount of oxygen b) methane limiting c) oxygen limiting a) CH4 + 2 O2 → CO2 + 2 H2O 2 mole O2 1 mol CH4 6 mole O2 3 mol CH4 2 1 stoichiometry: = want a) have 21 given: = b) b) c) c) c) Wood, 2006
limiting reactants 2 SO2(g) + O2(g) → 2 SO3(g) Given 3.0 moles of SO2. O2 would be the limiting reactant if we had less than ___ mol O2 1.5 Given 5 moles of O2. SO2 would be the limiting reactant if we had less than ___ mol SO2 10 Given 3.5 moles of O2. SO2 is in excess if we had more than ___ mol SO2 7.0 Given 1.5 moles of SO2. O2 is in excess if we had more than ____ mol O2 a) 0.75 0.75 b) 1.5 c) 10 d) 7.0 3.5 e)
calculations with equations If you have 8 moles of hydrogen gas and all the oxygen gas you need, how many moles of water can you make? If you have all the hydrogen gas that you need and 8 moles of oxygen gas, how many moles of water can you make? If you have 8 moles of hydrogen gas and 9 moles of oxygen gas, how many moles of water can you make? O2+ 2 H2→2 H2O a) 1 mol b) 2 mol c) 4 mol d) 8 mol e) 16 mol stoich: 21 = 2 mol H2 1 mol O2 8 mol H2 9 mol O2 limiting a) 0.891 given: = b) c) d) e)
limiting reactants tip: whenever the mass or amount of both reactants are given, you can bet your bottom dollar that one of the reactants will be limiting challenging problem: sodium hydroxide reacts with carbon dioxide to give solid sodium carbonate and liquid water. when 1.70 mol sodium hydroxide is reacted with 1.00 mol carbon dioxide, the actual yield was found to be 93.3%. how many grams of sodium carbonate was produced?