OCTOBER 15 & MS. BOON CHEMISTRY Stoichiometry 1

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 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

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. SCl C 2 H 4 → (ClCH 2 CH 2 ) 2 S If you have 10 g SCl 2 and 100 g C 2 H 4, how many grams of mustard gas can you make? Why?

Where are we going with this?

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 + O 2  MgO 2 Mg + O 2  2 MgO

Finding the molar ratio -- Example 1: 2 Mg + O 2  2 MgO 1.What is the ratio of moles Mg atoms to moles O 2 molecules? A: There are 2 moles Mg atoms for every 1 mole O 2 molecules. The ratio is 2:1. Write this ratio as a fraction: 2 mol Mg 1 mol O 2

Example 2: CH O 2 → CO H 2 O 1.What is the ratio of moles CH 4 to moles O 2 ? 2.What is the ratio of moles O 2 to moles CO 2 ? 3.What is the ratio of moles H 2 O to moles CH 4 ? 4.What is the ratio of moles CO 2 to moles H 2 O? 1 mol CH 4 2 mol O 2 1 mol CO 2 2 mol H 2 O 1 mol CH 4 1 mol CO 2 2 mol H 2 O

Quick Check Question Do the following problem in your notes. 2 NI 3  N I 2 What is the mole ratio of NI 3 to N 2 ? Vote for your answer: 1) 1 mol NI 3 2 mol N 2 2) 2 mol NI 3 2 mol N 2 3) 2 mol NI 3 1 mol N 2 4) 3 mol NI 3 2 mol N 2

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) 2 FeO + 1 C  2 Fe + 1 CO 2 2) 2 NO + 1 O 2  1 NO 2 3) 1 CH S  1 CS H 2 S Balance the equations and then give the ratio between the two compounds in bold red. 4)__PCl 3 +__H 2 O  __H 3 PO 3 +__HCl 5)___Xe + ___F 2  ___XeF 4 6)__Al +__HCl  __AlCl 3 +__H 2

Mole to Mole Conversions: Example 1 2 Mg + O 2  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 X 12 mol Mg = 12 mol MgO

Mole to Mole Conversions: Example 2 CH O 2 → CO H 2 O How many moles of CH 4 are needed to form 30 moles of H 2 O? What are we converting? Mol H 2 O to Mol CH 4 Step 1: Write the mole ratio with the unknown units on top. Step 2: multiply by the given moles. 1 mol CH 4 2 mol H 2 O X 30 mol H 2 O = 15 mol CH 4

Quick Check Question Do the following problem in your notes. 2 NI 3  N I 2 How many moles NI 3 are required to produce 10 moles N 2 ? Vote for your answer: 1) 10 mol NI 3 2) 20 mol NI 3 3) 5 mol NI 3 4) 40 mol NI 3

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 KClO 3 (s) → 2 KCl (s) + 3 O 2 (g) 1. What is the mole ratio of KCl to O 2 ? 2. What is the mole ratio of KCl to KClO 3 ? 3. How many moles O 2 will be produced from 4 moles KClO 3 ? 4. How many moles KClO 3 are required to produce 32 moles KCl?