2 What is it?Study of quantitative relationships between amounts of reactants used and products formed by a chemical reactionBased on the law of conservation of mass
3 2 slices of bread + 1 slice of cheese 1 grill cheese sandwich Recipe2 slices of bread + 1 slice of cheese 1 grill cheese sandwichWhy is it important to know the recipe?To determine how much is needed or how much will be producedHow many sandwiches can you make if you have 20 slices of bread and LOTS of cheese?
4 Interpreting the Equations When looking at a balanced equation, the coefficients can represent:The number of molecules- a literal interpretationThis means 2 molecules of hydrogen will react with 1 molecule of oxygen to give 2 molecules of water.2 H2 + O2 2H20
5 Interpreting the Equations The coefficients can also represent:The number of moles of each moleculeThis means 2 moles of hydrogen will react with 1 mole of oxygen to give 2 moles of water.2 H2 + O2 2H20
6 Interpreting the Equations The coefficients can also represent:The number of volumes of gas in a reaction- ONLY if the molecules are gas molecules2 volumes of hydrogen reacts with 1 volume of oxygen will give 2 volumes of water.2 H2 (g) + O2 (g) 2H20 (g)
7 Mole Ratios = Conversion Factors What is it?A ratio between the numbers of moles of any two substances in a balanced chemical equation2H2 + O2 2H20What are the 3 different equivalencies that exist?2 mol H2 ≈ 1 mol O22 mol H2 ≈ 2 mol H2O1 mol O2 ≈ 2 mol H2O
8 Mole Ratios From each equivalency, two mole ratios can be formed: 2 mol H2/1 mol O mol O2/2 mol H22 mol H2/2 mol H2O 2 mol H2O/2 mol H21 mol O2/2 mol H2O 2 mol H2O/1 mol O2Which mol ratio is used depends on which ratio is needed when doing unit analysis, or which one the question asks for.
9 N2 + H2 NH3If you start with 3.0 moles of N2, how many moles of H2 are needed? How many moles of NH3 can be produced?1. Balance the reaction:N2 + 3 H2 2 NH32. Write out the equivalencies:1 mol N2 ≈ 3 mol H mol N2 ≈ 2 mol NH mol H2 ≈ 2 NH33. Set up the unit analysis
10 N2 + 3 H2 2 NH3To solve for H2: 3.0 mol N2 3 mol H2 = 9.0 mol H2 1 mol N2 To solve for NH3: 3.0 mol N2 2 mol NH3 = 6.0 mol NH3 The mole ratios are conversion factors using the coefficients from the balanced equation.
11 N2 + 3H2 2NH3How many moles of nitrogen must react to produce 2.18 moles of ammonia?
12 Moles of A to Mass of BYou can never convert directly from moles of A to grams of BYou must go through the moles!!
13 Double Flux Capacitor Particles A Mass A Particles B Mass B Mole Ratio Moles BMoles A*draw stuff on lines on boardVolume AVolume B
14 1N2 (g) + 3H2 (g) 2NH3 (g)How many grams of nitrogen must react with 2.3 moles of hydrogen?
15 1N2 (g) + 3H2 (g) 2NH3 (g)How many grams of NH3 are produced if 2.3 moles of hydrogen is reacted with excess nitrogen?
16 Mass A to Mass B You can never go from A to B without moles!! Steps: 1) Convert the initial value to moles1 mole A = grams A2) Use Mole A to Mole B ratio from equation3) Convert Moles B to grams of B1 mole B= grams B
17 N2 (g) + 3H2 (g) 2NH3 (g)How many grams of NH3 are produced if 15 grams of hydrogen is reacted with excess nitrogen?
18 N2 (g) + 3H2 (g) 2NH3 (g)How many grams of nitrogen reacted if grams of NH3 is produced?
19 Mass A to Particles B or Particles A to Mass B You can never go from A to B withoutmoles!!Steps (mass particles):1) Convert the initial value to moles1 mole A = grams A2) Use Mole A to Mole B ratio from equation3) Convert Moles B to particles of B1 mole B= 6.02x1023 particles B
20 N2 (g) + 3H2 (g) 2NH3 (g)How many particles of NH3 are produced if 22 grams of hydrogen is reacted with excess nitrogen?
21 N2 (g) + 3H2 (g) 2NH3 (g)How many grams of nitrogen reacted if 7.1x1023 molecules of NH3 is produced?
22 Mass A to Volume B (gas) 1 mole A = grams A 1 mole B= 22.4L B To find volume, the reaction must occur at STP.To go between A and B, you must first find moles!Steps:1) Convert the initial value to moles1 mole A = grams A2) Use Mole A to Mole B ratio from equation3) Convert Moles B to Liters of B1 mole B= 22.4L B
23 1N2 (g) + 3H2 (g) 2NH3 (g)How many grams of nitrogen are needed if 33 liters of ammonia is produced?
24 1N2 (g) + 3H2 (g) 2NH3 (g)How many liters of ammonia are produced if 55 grams of nitrogen is reacted with excess hydrogen?
25 Mixed problemsHow many grams of water are produced if 15 grams of hydrogen are reacted?H2(g) + O2 (g) H20 (g)
26 2 H2(g) + O2 (g) 2H20 (g)How many liters of oxygen is reacted if 3.4x1023 molecules of water is produced?
27 Theoretical vs. Actual Yield Theoretical yieldMaximum amount of product that can bemade from given amounts of reactantsWhat you do on paperActual yieldThe amount of product that ACTUALLY forms when the reaction is carried out in the lab
28 Percent Yield Percent yield = actual yield theoretical yield X 100% The % yield should always be less than 100 % due to experimental error. When plugging in the theoretical yield, always use the UNROUNDED value.
29 Percent Yield What is the percent yield if the theoretical yield is 120 grams, but in the experiment only 87 grams is produced?
30 The actual yield will always be one of the products The actual yield will always be one of the products. It can never be one of the reactants.Na + H2O NaOH + H2If 18.3 g of sodium can produce 8.23 liters of hydrogen gas, what is the % yield?Balanced equation: 2Na + 2H2O 2NaOH + H218.3 g Na 1 mol Na 1 mol H L H2 = 8.91 L H223.0 g Na 2 mol Na 1 mol H2(8.23 L H2 / … L H2) x 100 % = 92.4 %
31 Limiting Reactant vs. Excess What is a limiting reactant?The reactant that LIMITS the reactionThe reactant that is completely used upLimiting reactant determines how much product is madeWhat is an excess reactant?The reactant that is not completely used up
32 AB+ CD AD2 + C2B Balance equation Label information for each reactant/productConvert reactant (or product) to moles, if neededSolve for one substance on the opposing side of the equationThe limiting reagent produces the least amount of product
33 H2(g) + O2 (g) H20 (g)Identify the limiting reactant when 1.22 gram of oxygen reacts with 1.05 grams of hydrogen to produce water
34 PracticeIf 4.1 grams of Cr is heated with 9.3 grams of Cl2, what mass of CrCl3produced?