Chemistry Tuesday, February 14 Wednesday, February 15, 2017

Transcription

1 Chemistry Tuesday, February 14 Wednesday, February 15, 2017 Do-Now: BrainPOP: Moles 1. Write down today s FLT 2. What are the units of molar mass? 3. Use your periodic table to find the molar mass of NaOH. 4. How many moles is 5.69 g of NaOH? Show all work and units. Check sig figs. 3. Number 1-10 under your do-now for our BrainPOP Take out your planner and ToC Announcements No School Mon 2/20 Labs & Quiz Packets No tutoring a<er school Thurs We will be finishing our ToC à get ALL stamps! Planner: Finish problem WS show all work Get STAMPS J J J Begin reading Ch. 12 Table of Contents #1: 20. BrainPOP: Moles Notes Review Sheet BrainPOP: Moles Watch the BrainPOP video A<er the video, answer the queslons in your group every member must copy down the same answer The group with the most correct answers à +5 dojo points each h5ps:// FLT I will be able to identify the volume of a quantity of gas at STP by completing 10.2 Cornell Notes Standard HS-PS1-7: Use mathemaccal representacons to support the claim that atoms, and therefore mass, are conserved during a chemical reaccon 1

2 10.2: Mole-Mass and Mole-Volume Recall Moles ßà Particles Moles ßàMass Mole-Volume Relationship What are the units for volume? Liters! Mole Volume Relationship 2

3 Mole-Volume Relationship Many of the chemicals we deal with are in the physical state as GASES They are difficult to mass Consequently, we often use VOLUME for gases Mole-Volume Relationship Volume may be affected by (1) Temperature (2) Pressure Consequently, we need to compare gases at a constant temperature and pressure for consistency Mole-Volume Relationship Standard Temperature and Pressure (STP): 1 atm of pressure and 273 K (0 C) Mole-Volume Relationship Molar Volume: At STP, 1 mole of any gas occupies a volume of 22.4 L Example 1 What is the volume of 4.59 mole of CO 2 gas at STP? Sample Problems 3

4 Example 2 How many moles is 5.67 L of O 2 at STP? Recall Density = mass/volume (g/l) Example 3 The density of a gas is g/l at STP. What is the molar mass of the gas? Example 4 The density of a gas is 3.58 g/l at STP. What is the molar mass of the gas? CW Ch. 10 Review Sheet Show all work and units clearly Check sig figs ToC and/or study Ch. 10 Chemistry Thursday, February 16 Friday, February 17,

5 Do-Now: Ch. 12 Notes A 1. Write down today s FLT 2. What is meant by the term STP? 3. Write the conversion from moles to liters at STP. 4. Balance the following equation (showing all work): Fe + AgNO 3 à Fe(NO 3 ) 2 + Ag Take out your planner and ToC Announcements No School Mon 2/20 Turn in missing work! Use dojo points! Get ALL stamps Begin studying for unit test: Ch. 3, Emphasis on Ch.12 Planner: Finish WS & get stamps Study for Unit Test (Ch. 3, 10-12) Lab next Thurs/Fri Table of Contents #1: 23. Ch. 12 Notes A WS FLT I will be able to interpret balanced chemical equations in terms of moles, particles, mass, and gas volumes at STP by completing Ch. 12 Notes A Standard HS-PS1-7: Use mathemaccal representacons to support the claim that atoms, and therefore mass, are conserved during a chemical reaccon Ch. 12 Notes A: Stoichiometry Recall 5

6 Conversions Particles (atoms, molecules, formula units) Mole Mass (g) Volume (L) Chemical Equations What does each part of a balanced chemical equation represent? What does a balanced chemical equation tell us? Balanced Chemical Equations When baking cookies, a recipe is usually used, telling the exact amount of each ingredient. If you need more, you can double or triple the amount Stoichiometry Stoichiometry Greek for measuring elements Stoichiometry = the calculation of quantities in chemical reactions All stoichiometric calculations must begin with a balanced chemical equation 6

7 Balanced Chemical Equations Four ways interpret a balanced chemical equation: Moles Particles (atoms, molecules, formula units) Mass Volume Mole Ratios 2H 2 + O 2 à 2H 2 O For every two moles of hydrogen and one mole of oxygen, 2 moles of water form 2 mol H 2 : 1 mol O 2 : 2 mol H 2 O 4Al + 3O 2 à 2Al 2 O 3 Interpret the equation above in terms of moles Mole Ratios Use coefficients in balanced eqs to write ratios or conversion factors 2Na + 2H 2 O 2NaOH + H 2 Try This: Write all of the possible mole ratios for this equation: 2Al 2 O 3 4Al + 3O 2 7

8 Example 2H 2 + O 2 à 2H 2 O How many moles of oxygen gas will be required to react with sufficient hydrogen in order to produce 5 moles of H 2 O? Try This: 2N 2 + 3O 2 à 2N 2 O 3 How many moles of oxygen gas will be required to react with sufficient nitrogen in order to produce 21 moles of N 2 O 3? Particles Balanced Chemical Equations Coefficients can also be used to represent relative numbers of particles (atoms, molecules, formula units) 2SO 2 + O 2 à 2SO 3 2 moles SO 2 : 1 mole O 2 : 2 moles SO 3 2 molecules of SO 2 : 1 molecule of O 2 : 2 molecules of SO 3 Try This: 2H 2 + O 2 à 2H 2 O Interpret the above in terms of molecules 8

9 Volume Volume If we are at STP We can interpret the coefficients as relative volumes 2H 2 + O 2 2H 2 O (2 x 22.4 L H 2 ) + (1 x 22.4 L O 2 ) (2 x 22.4 L H 2 O) Volume At STP, 1 mol of any gas = 22.4 L 2H 2 + O 2 2H 2 O (2 x 22.4 L H 2 ) + (1 x 22.4 L O 2 ) (2 x 22.4 L H 2 O) 67.2 Liters of reactant 44.8 Liters of product! NOTE: mass and atoms are ALWAYS conserved - however, molecules, formula units, moles, and volumes will not necessarily be conserved! Mass Mass Recall: The Law of Conservation of Mass Since mass and atoms are conserved, we can also use mole ratios to determine mass Example 2H 2 + O 2 à 2H 2 O The mass of the reactants must equal the mass of the products. 9

10 Try This: Show that the following follows the Law of Conservation of Mass (show the atoms balance & the mass on both sides is equal) 2Al 2 O 3 4Al + 3O 2 Mass 2H 2 + O 2 à 2H 2 O What mass of hydrogen will need to react with 30.0 grams of oxygen? à We ll practice this Tues/Wed next week J CW 12.1 WS ToC and/or study Ch