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Thursday, Sept. 26 th : “A” Day Friday, Sept. 27 th : “B” Day Agenda. Homework Questions/Problems Quick Review (Practice #2c; Practice #1: c, d) Finish Sec 9.1: “Calculating Quantities in Reactions” Calculations involving volume and number of particles In-Class/Homework: - PowerPoint PPT Presentation

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Page 1: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda
Page 2: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda
Page 3: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Thursday, Sept. 26th: “A” DayFriday, Sept. 27th: “B” Day

Agenda

Homework Questions/Problems Quick Review (Practice #2c; Practice #1: c, d) Finish Sec 9.1: “Calculating Quantities in Reactions”

Calculations involving volume and number of particles

In-Class/Homework:Problem Solving Supplement Worksheet

Page 4: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Practice #2c, pg. 304Calculate the amounts requested if 3.30 mol

Fe2O3 completely react according to the following equation:

Fe2O3 + 2 Al 2 Fe + Al2O3

c) Mole of aluminum oxide formed3.30 mol Al2O3

Page 5: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Practice #1, pg. 307Use the equation below to answer the questions

that follow:

Fe2O3 + 2Al 2Fe + Al2O3

c) How many grams of Fe2O3 react with excess Al to make 475 g Fe?

679 g Fe2O3

d)How many grams of Fe will form when 97.6 g Al2O3 form?

107 g Fe

Page 6: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Stoichiometry Calculations involving Volume

When reactants are liquids, they are almost always measured by volume.

To convert from volume mass ormass volume, use the density of the substance as the conversion factor.

Units for density are typically: g/mL, g/cm3, or g/L

Page 7: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Other ways to include volume in stoichiometry calculations:

1. If the substance is a gas at standard temperature and pressure, STP, use the molar volume of the gas.The molar volume of ANY gas at STP is:

22.41 L/mol

**STP is 0˚C and 1 atm***

Page 8: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Other ways to include volume in stoichiometry calculations:

2. If the substance is in aqueous solution, use the concentration of the solution, in mol/L, to convert the volume of the solution to the moles of the substance dissolved.

Stay with me, it’ll make sense once we get there….

Page 9: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Sample Problem C, pg. 309What volume of H3PO4 forms when 56 mL of POCl3

completely react? POCl3 + 3 H2O H3PO4 + 3 HCl(density of POCl3 = 1.67 g/mL)

(density of H3PO4 = 1.83 g/mL)

Remember our 3 steps:1.Change the units of what you know into moles.2.Use the mole ratio to determine moles of desired

substance.3.Change out of moles into the unit you want.

Page 10: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Sample Problem C (continued)What volume of H3PO4 forms when 56 mL of POCl3 completely

react? POCl3 + 3 H2O H3PO4 + 3 HCl

(density of POCl3 = 1.67 g/mL)

(density of H3PO4 = 1.83 g/mL)

1.Start with what you know: 56 mL POCl3

2.Use the density to change mL POCL3 g POCl3

56 mL POCl3 X 1.67 g POCL3 = 93.52 g POCl3

1 mL POCl3

3.Use molar mass to change g POCl3 mol POCl3

93.52 g POCl3 X 1 mol POCl3 = .61 mol POCl3

153.32 g POCl3

Page 11: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Sample Problem C (continued) What volume of H3PO4 forms when 56 mL of POCl3

completely react? POCl3 + 3 H2O H3PO4 + 3 HCl

(density of POCl3 = 1.67 g/mL)

(density of H3PO4 = 1.83 g/mL)

4.Use mole ratio to change mol POCl3 mol H3PO4

0.61 mol POCl3 X 1 mol H3PO4 = .61 mol H3PO4

1 mol POCl3

5.Use molar mass to change mol H3PO4 g H3PO4

0.61 mol H3PO4 X 98.00 g H3PO4 = 59.78 g H3PO4

1 mol H3PO4

Page 12: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

What volume of H3PO4 forms when 56 mL of POCl3 completely react? POCl3 + 3 H2O H3PO4 + 3 HCl

(density of POCl3 = 1.67 g/mL)

(density of H3PO4 = 1.83 g/mL)

6. Use the density to convert g of H3PO4 mL H3PO4

59.78 g H3PO4 X 1 mL H3PO4 =33 mL H3PO4 1.83 g H3PO4

Wow, I know that’s a lot of steps, but this is as difficult as it gets….

Sample Problem C (continued)

Page 13: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Use the densities and the balanced equation provided to answer the questions that follow.

C5H12 C5H8 + 2 H2

(density of C5H12 = 0.620 g/mL)(density of C5H8 = 0.681 g/mL)(density of H2 = 0.0899 g/L)1. How many mL of C5H8 can be made from 366 mL

C5H12?315 mL C5H8

2. How many L of H2 can form when 4.53 X 103 mL C5H8 form?

2.03 X 103 L H2

Practice

Page 14: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Stoichiometry Calculations Involving Number of Particles

You can use Avogadro’s number as a conversion factor in stoichiometry problems involving particles, atoms, molecules, etc.

6.022 X 1023= 1 mole

Page 15: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Sample Problem D, pg. 310How many grams of C5H8 form from

1.89 X 1024 molecules of C5H12?

C5H12 C5H8 + 2 H2

1. Start with what you know and change to moles: 1.89 X 1024 molecules C5H12 X 1 mol C5H12

6.022 X 1023 molecules= 3.14 mol C5H12

2. Use mole ratio to change mol C5H12 mol C5H8

3.14 mol C5H12 X 1 mol C5H8 = 3.14 mol C5H8

1 mol C5H12

Page 16: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Sample Problem D (Continued)How many grams of C5H8 form from

1.89 X 1024 molecules of C5H12?

C5H12 C5H8 + 2H2

3. Use molar mass to change mol C5H8 g C5H8

3.14 mol C5H8 X 68.13 g C5H8 =

1 mol C5H8

214 g C5H8

Page 17: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Practice #1, pg. 311

Use the equation below to answer the questions that follow:

Br2 + 5 F2 2 BrF5

1.How many molecules of BrF5 form when

384 g Br2 react with excess F2?

2.89 X 1024 molecules BrF5

Page 18: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

Stoichiometry Problem SolutionsUpdate your graphic organizer:1.What do you use to change from

Volume MolesDensity: (g/mL) or (g/cm3) or (g/L)

Gas @ STP: 22.41 L/molConcentration: (mol/L)

2.What do you use to change from Molecules or Particles Moles

Avogadro’s Number6.022 X 1023 = 1 mole

Page 19: Thursday, Sept. 26 th :  “A” Day Friday, Sept. 27 th :  “B” Day Agenda

In-Class/HomeworkProblem Solving Supplement Worksheet

Looking Ahead:Next time, you’ll work on the section

review and the concept review in class before taking a quiz over this

section…