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Stoichiometry 1. October 15 & 16 2012 Ms. Boon Chemistry. Catalyst: A cookie recipe requires 1 cup of sugar, 2 cups of flour, 1 stick of butter and 3 eggs. How much of each ingredient do you need in order to double the recipe? Explain your answer. Objective:
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Stoichiometry 1 October 15 & 16 2012 Ms. Boon Chemistry
Catalyst: • A cookie recipe requires 1 cup of sugar, 2 cups of flour, 1 stick of butter and 3 eggs. • How much of each ingredient do you need in order to double the recipe? Explain your answer. Objective: I can create mole ratios from a balanced chemical equation and perform mole to mole conversions. Agenda: Catalyst Notes: Stoichiometry Practice: Mole Ratios Notes: Mole to mole Practice: mole to mole Exit Slip
Today’s Schedule Objective: I can create mole ratios from a balanced chemical equation and perform mole to mole conversions. Agenda: Catalyst Notes: Stoichiometry Practice: Mole Ratios Notes: Mole to mole Practice: mole to mole Exit Slip
Notes: What is stoichiometry? Stoichiometry is the study of the relationships between quantities of substances in chemical reactions.
Where are we going with this? By the end of the unit, we will be able to solve questions like this: Mustard gas (chemical warfare agent used in World War 1) is synthesized by the reaction of sulfur dichloride and ethylene. SCl2 + 2 C2H4 → (ClCH2CH2)2S If you have 10 g SCl2 and 100 g C2H4, how many grams of mustard gas can you make? Why?
What is a Ratio? • A "ratio" is just a comparison between two different things • Ex.: A cookie recipe requires 1 cup of sugar, 2 cups of flour, 1 stick of butter and 3 eggs. • What is the ratio of sugar to flour? • What is the ratio of butter to eggs? • Ratio of eggs to flour? • What if you wanted to “double” the recipe?
You can use ratios for moles too!-Balance the following reaction, label the reactants and the product. Mg + O2 MgO 2 Mg + O2 2 MgO
Finding the molar ratio -- Example 1: 2 Mg + O2 2 MgO • What is the ratio of moles Mg atoms to moles O2 molecules? • A: There are 2 moles Mg atoms for every 1 mole O2 molecules. • The ratio is 2:1. • Write this ratio as a fraction: 2 mol Mg • 1 mol O2
Example 2: CH4 + 2 O2 → CO2 + 2 H2O 1 mol CH4 2 mol O2 What is the ratio of moles CH4 to moles O2? What is the ratio of moles O2 to moles CO2? What is the ratio of moles H2O to moles CH4? What is the ratio of moles CO2 to moles H2O? 2 mol O2 1 mol CO2 2 mol H2O 1 mol CH4 1 mol CO2 2 mol H2O
Quick Check Question Do the following problem in your notes. 2 NI3 N2 + 3 I2 What is the mole ratio of NI3 to N2? Vote for your answer: 2) 2 mol NI3 2 mol N2 1) 1 mol NI3 2 mol N2 4) 3 mol NI3 2 mol N2 3) 2 mol NI3 1 mol N2
Practice Problems Set 1 Complete the following problems in your notes. Give the mole ratio between the two compounds that are in bold red.1) 2FeO + 1 C 2 Fe + 1CO2 2) 2 NO + 1O2 1NO2 3) 1 CH4 + 4S 1 CS2 + 2H2S Balance the equations and then give the ratio between the two compounds in bold red. 4)__PCl3 +__H2O __H3PO3 +__HCl 5)___Xe + ___F2 ___XeF4 6)__Al +__HCl__AlCl3 +__H2
Mole to Mole Conversions: Example 1 2 Mg + O2 2 MgO How many moles of MgO can be made from 12 moles of Mg? What are we converting? Mol Mg to Mol MgO Step 1: Write the mole ratio with the unknown units on top. Step 2: multiply by the given moles. 2 mol MgO 2 mol Mg 12 mol Mg X = 12 mol MgO
Mole to Mole Conversions: Example 2 CH4 + 2 O2 → CO2 + 2 H2O How many moles of CH4 are needed to form 30 moles of H2O? What are we converting? Mol H2O to Mol CH4 Step 1: Write the mole ratio with the unknown units on top. Step 2: multiply by the given moles. 1 mol CH4 2 mol H2O 30 mol H2O X = 15 mol CH4
Quick Check Question Do the following problem in your notes. 2 NI3 N2 + 3 I2 How many moles NI3 are required to produce 10 moles N2? Vote for your answer: 2) 20 mol NI3 1) 10 mol NI3 4) 40 mol NI3 3) 5 mol NI3
Mole to Mole Conversion Practice Complete the worksheet problems on your notes. Work quietly with the people around you. Show all your work. Tonight’s HW: Read p. 302 – 305; Do practice problems p. 304 #1 & 2, p. 311 #1, 4(a), 6.
Exit Slip 2 KClO3 (s) → 2 KCl (s) + 3 O2 (g) What is the mole ratio of KCl to O2? What is the mole ratio of KCl to KClO3? How many moles O2 will be produced from 4 moles KClO3? How many moles KClO3 are required to produce 32 moles KCl?