Warm-up 5/13/13 From the Activity last class: 1 M C 2 → 2 MC 3 1.What is the ratio of M 2 /MC 3 ? 2.What is the ratio of C 2 /MC 3 ? 3.How could you find these without actually counting paperclips? 4.How many MC 3 compounds could be produced from 24 M 2 ? (assume you have an unlimited supply of C 2 )

I. Introduction 1.Stoichiometry: Describes the quantitative relationships among substances in a chemical reaction ▫Derived from the Greek words stoicheion "element" and metron "measure" 2.Why is this important? Describes how much will be made from a chemical reaction (or how much is needed).

N 2(g) +3H 2(g) → 2NH 3(g) 1. Particles 2 atoms N 6 atoms H 2 atoms N 6 atoms H 1 molecule3 molecules2 molecules

N 2(g) +3H 2(g) → 2NH 3(g) 2. Moles 1 mole3 moles2 moles

N 2(g) +3H 2(g) → 2NH 3(g) 3. Mass 1*2(14.007) g 3*2(1.008) 6.048g 2*1(14.007)+3(1.008) g g Reactants g Products

N 2(g) +3H 2(g) → 2NH 3(g) 4. Volume 1*22.4L 22.4L 3*22.4L 67.2L 2*22.4L 44.8L

N 2(g) +3H 2(g) → 2NH 3(g) 1. Particles 2 atoms N 6 atoms H 2 atoms N 6 atoms H 1 molecule3 molecules2 molecules 2. Moles 1 mole3 moles2 moles 3. Mass 1*2(14.007) g 3*2(1.008) 6.048g 2*1(14.007)+3(1.008) g g Reactants g Products 4. Volume 1*22.4L 22.4L 3*22.4L 67.2L 2*22.4L 44.8L

II. Map

One Step Problems 1. Mole – Mole a.What is a mole ratio? A comparison of the coefficients from a balanced chemical equation. b.Example: ▫Start with a balanced reaction: 2Al 2 O 3 → 4Al + 3O 2 Use the coefficients to determine the mole ratios.

____CO 2 + ____LiOH  ____Li 2 CO 3 + ____H 2 O 1) How many moles of LiOH are required to react with 20 mol of CO 2 ? 2) How many moles of Li 2 CO 3 will be produced from 3.5 moles of LiOH?

_____ H 2 + _____ N 2  _____NH 3 1) How many moles of H 2 are required to form 5.0 moles of NH 3 ? 2) Find the number of moles of N 2 needed to react completely with 4.52mol of H 2.

_____ H 2 + _____ N 2  _____NH 3 3) How many moles of N2 will be needed to form 6.0 moles of NH3? 4) 10 moles of H2 will form how many moles of NH3?

IV. Multiple Step Problems 1.For these problems you will need: Balanced Equation Map UNITS!

_____ KClO 3  _____KCl + _____O 2 1. Potassium chlorate decomposes to produce potassium chloride and oxygen. How many grams of potassium chlorate are required to produce moles of oxygen?

2 KClO 3  2 KCl + 3 O 2 2. Using the same balanced equation above, how many moles of potassium chlorate are needed to produce 250 grams of oxygen.

2 KClO 3  2 KCl + 3 O 2 3. If you begin with 5.0g of potassium chlorate, what is the mass of potassium chloride that will be produced?

_____NH 4 NO 3  _____N 2 + _____O 2 +_____ H 2 O 1) Ammonium nitrate is found in fertilizers and high explosives. It is unstable and decomposes into several gases, nitrogen and oxygen, as well as water. The rapid expansion of the gases produces the explosive force. Find the mass of water produced from grams of the ammonium nitrate

_____ZnS + _____O 2  _____ZnO + _____ SO 2 The white solid found in some sunblock is zinc oxide. This is produced by burning zinc sulfide in oxygen. 2) To produce 10.0 grams of zinc oxide, how many grams of zinc sulfide are used?

VI. Percent Yield 1.Definition: ▫the ratio of the actual yield to the theoretical yield ▫A measure of the efficiency of a reaction 2.Equation: Actual x 100 Theoretical

VI. Percent Yield 1. Lead nitrate can be decomposed by heating. What is the percent yield of the decomposition reaction if 9.9g of Pb(NO 3 ) 2 are heated to give 5.5g of PbO? 2Pb(NO 3 ) 2 → 2PbO + 4NO 2 + O 2 Actual x 100 Theoretical

VI. Percent Yield 2. Hydrogen gas is produced when zinc reacts with hydrochloric acid. If the actual yield of this reaction is 85%, how many grams of zinc are needed to produce 112L of H 2 at STP? Zn + 2HCl → ZnCl 2 + H 2 Actual x 100 Theoretical