Percent Composition, Empirical Formulas, Molecular Formulas - PowerPoint Presentation

Slide1

Percent Composition, Empirical Formulas, Molecular Formulas

Week 22 ChemistrySlide2

Warm Up:

3

Minutes

A certain bag of M&M’s has 8 blue candies, 7 red candies, 4 green candies, and 6 yellow candies. What percentage of the bag is blue M&M’s?

Record your Learning Target

You should be working SILENTLY

Stay in your own seat

Do the warm up in OneNoteSlide3

Agenda

Warm Up

[6

minutes]Pre-Lab/Expectations [7 minutes]Bubble Gum Lab

[18 minutes]Answer Key [ 4 minutes]

Modeling Tracking [5 minutes]You Track [10 minutes]Closing [3 Minutes]Slide4

Bubble Gum LabSlide5

P

roblem

What percentage of Double Bubble Gum is composed of sugar?Slide6

Pre-Lab Question

According

to the nutritional manufacturer, each piece of gum has a mass of 6g with 5g of sugar. Using this information, what percent of the gum is sugar by mass?

 Slide7

Lab Expectations

Work in assigned groups

Raise your hand if you have a question

No gum should be left on the desksSlide8

General information: How to do the lab

Find the mass of your piece of gum before chewing (include the wrapper)

Chew your gum for ~5 minutes

Find the mass of your piece of gum after chewing

Gum should be placed in wrapper before putting it on mass balanceComplete analysis and post-lab questionsSlide9

Bubble Gum Lab

You each need

One Piece of Gum

and your Brain

Good Luck!!!

15 MinutesSlide10

Answer Key

As Mr. Ghosh goes through the answers, highlight the ones you got wrong

A

CA

DDCA

DCBB12. B13. B14. A15. C

16. A17. C18. A19. A20. B21. CSlide11

Class Averages (and Top Scores)

Period

Top Score

Class Average

1

95%60%3100%70%4

90%79%590%71%

6100%66%795%

64%Slide12

What does Tracking Look Like?

Objectives

Questions on the Exam

Your Points

Total

PointsPercent MasteryBar GraphMastery85%

  or Chem.7C Lewis Dot StructuresSlide13

What does Tracking Look Like?

Objectives

Questions on the Exam

Your Points

Total

PointsPercent MasteryBar GraphMastery85%

  or Chem.7C Lewis Dot Structures1-5Slide14

What does Tracking Look Like?

Objectives

Questions on the Exam

Your Points

Total

PointsPercent MasteryBar GraphMastery85%

  or Chem.7C Lewis Dot Structures1-5

???[3 if you got 3 out of 5 correct]Slide15

What does Tracking Look Like?

Objectives

Questions on the Exam

Your Points

Total

PointsPercent MasteryBar GraphMastery85%

  or Chem.7C Lewis Dot Structures1-5

???[3 if you got 3 out of 5 correct]5Slide16

What does Tracking Look Like?

Objectives

Questions on the Exam

Your Points

Total

PointsPercent MasteryBar GraphMastery85%

  or Chem.7C Lewis Dot Structures1-5

???[3 if you got 3 out of 5 correct]5Your points x100 Total pointsSlide17

Percent Mastery

Cathy received 1 point out of 4

possible points. What is

her percent mastery?

Your points x100 Total points

25%Slide18

What does Tracking Look Like?

Objectives

Questions on the Exam

Your Points

Total

PointsPercent MasteryBar GraphMastery85%

  or Chem.7C Lewis Dot Structures1-5

???[3 if you got 3 out of 5 correct]5Your points x100 Total pointsShade in your % masterySlide19

Your Turn

Go to

shschem.weebly.com

(our class website)Hover over my page:

Mr. Ghosh  Homework Assignments  ESL (or regular) ChemistryUnder Homework Assignments, there is a new one labeled “Unit 5 Tracking”

Download (and save) this and fill it outSlide20

Closing

Explain the purpose of today’s labSlide21

Warm Up:

4

Minutes

You should be working SILENTLY

Stay in your own seat

Log into your computer

Go to m.socrative.comEnter room number: 230538Finish all questionsWhen you are finished, check your grades on PS ConnectSlide22

Agenda

Warm Up

[7 minutes]

Notes/Examples [15 minutes]Guided Practice [12 minutes]Independent Practice

[15 minutes]Closing [3 Minutes]Slide23
Slide24

What is

% Composition??

Percent by mass of each

element in a compoundSlide25

What is

% Composition??

 Slide26

Example 1:

A compound contains 2.0g of sodium, 3.5g of oxygen, and 0.5 g of hydrogen. What is the percent composition of this compound?Slide27

Example 2:

What is the percent composition by mass of the elements in the compound, AgNO

3

?Slide28

Guided Practice

Teacher:

1. Will show the problem on the board

Students:Take 24 seconds to

identify your given and unknown. Take 46 seconds to speak with your shoulder partner about the problem

Be ready to share when Mr. Ghosh says SWAGSlide29

Guided Practice 1:

9.03 g Magnesium combines completely with 3.48 g Nitrogen to form a compound. What is the percent composition of Nitrogen in this compound?

27.82 % NSlide30

Guided Practice 2:

What is the percent composition by mass of the elements in Mercury (II) Oxide?

92.6%

Hg

7.4%

OSlide31

Guided Practice

3

:

What is the percent composition by mass of the elements in K2CO3?

56.6% K

8.7% C34.7% OSlide32

Independent Practice

Take

some time to practice finding the %

composition of the following compounds

Practice makes Perfect

85%Slide33

Closing

How do you find the percent composition

of an element in a compound?Slide34

Warm Up:

4

Minutes

Write the Learning Target

You should be working SILENTLY

Stay in your own seat

Log into your computerGo to m.socrative.com

Enter room number: 230538Finish all questionsWhen you are finished, check your grades on PS ConnectSlide35

Agenda

Warm Up

[7 minutes]

Notes/Examples [15 minutes]Guided Practice [12 minutes]Independent Practice

[15 minutes]Closing [3 Minutes]Slide36

Goal For Today

Percent Composition:

79.8% C, 20.2% H

Student Given:

Student Answer:

CH3Slide37

Empirical Formulas

empirical formula of

glucose

= CH

2

O

Shows the lowest number ratio of atoms in a compoundSlide38

Example 1:

What is the empirical formula for a chemical compound that is 79.8% C and 20.2% H?Slide39

Step 1: Convert Percent to Grams

Step 2: Convert Grams to Moles by dividing grams by the atomic mass of each element

.

79.8% C and 20.2% H

How to Compose the Empirical Formula?Slide40

Step 3:Divide both molar quantities by the smallest mole quantity to determine the subscript for each element in the formula

79.8% C and 20.2% H

How to Compose the Empirical Formula?Slide41

Example 2:

What

is the empirical formula for a compound that is 81.7% Be and 18.3% H?Slide42

Guided Practice

Teacher:

1. Will show the problem on the board

Students:Take 22 seconds to

identify the elements involved. Take 68 seconds to solve the problem with your shoulder partner

Be ready to share when Mr. Ghosh says SWAGSlide43

Guided Practice 1:

What is the Empirical Formula of a

compound that is 67.6% Hg, 10.8% S, and

21.6 % O by mass?

HgSO

4Slide44

Guided Practice

2

:

What is the Empirical Formula of a compound that is 88.2 % Oxygen and 11.8% Hydrogen by mass?

H

2OSlide45

Guided Practice 3:

What is the empirical formula of a

compound that is made from 50

% Cesium and 50% Iodine by mass?

CsISlide46

Independent Practice

Practice makes Perfect

85%Slide47

Closing

What is the empirical formula?

How

do you compose the empirical formula?Slide48

Warm Up:

4

Minutes

You should be working SILENTLY

Stay in your own seat

Log into your computer

Go to m.socrative.comEnter room number: 230538Finish all questionsWhen you are finished, check your grades on PS ConnectSlide49

Agenda

Warm Up

[7 minutes]

Notes/Examples [15 minutes]Guided Practice [12 minutes]Independent Practice

[15 minutes]Closing [3 Minutes]Slide50

More Empirical Formulas!!Slide51

Writing Empirical Formulas

Most of the time, our mole ratios come out close to a whole number (~.9, ~.1):

Examples:

1.992

2

Ratio from Calculator

What we assume

16.00412

4.962

6.071

6

5

16

But what if our mole ratio comes out to something like 1.501? What do we do then? Slide52

Example 1:

What is the empirical formula for a chemical compound that is 49.1% Be and 50.9% N?Slide53

Common Decimals/Fractions

When we find a mole ratio that ends up close to a common decimal/fraction:

X

.33

X

.66

X

.75

X

.5

X

.25

We must multiply these ratio values by a specific numberSlide54

Mole Ratio

Multiply all mole ratios by

Table of Common Decimals/FractionsSlide55

Mole Ratio

Multiply all mole ratios by

X.5

Table of Common Decimals/FractionsSlide56

Mole Ratio

Multiply all mole ratios by

X.5

2

Table of Common Decimals/FractionsSlide57

Mole Ratio

Multiply all mole ratios by

X.5

2

X.33

Table of Common Decimals/FractionsSlide58

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333

Table of Common Decimals/FractionsSlide59

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333X.66

Table of Common Decimals/FractionsSlide60

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333X.663

Table of Common Decimals/FractionsSlide61

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333X.663

X.75Table of Common Decimals/FractionsSlide62

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333X.663

X.754Table of Common Decimals/FractionsSlide63

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333X.663

X.754X.25Table of Common Decimals/FractionsSlide64

Mole Ratio

Multiply all mole ratios by

X.5

2

X.333X.663

X.754X.254Table of Common Decimals/FractionsSlide65

Example 1:

What is the empirical formula for a chemical compound that is 49.1% Be and 50.9% N?Slide66

Example 2:

What is the empirical formula of a compound that is 25.9% Nitrogen and 74.1 % Oxygen by mass?Slide67

Guided Practice

Teacher:

1. Will show the problem on the board

Students:Take 22 seconds to

identify the elements involved. Take 68 seconds to solve the problem with your shoulder partner

Be ready to share when Mr. Ghosh says SWAGSlide68

Guided Practice 1:

What is the Empirical Formula of a

compound that is

25.9% P and 74.1% Cl?

P

2Cl5Slide69

Guided Practice

2

:

What is the Empirical Formula of a compound that is 17.4% Nitrogen and 82.6% Fluorine?

N2F

7Slide70

Guided Practice 3:

What is the Empirical Formula of a compound that is made from 35.9% Aluminum and 64.1% Sulfur?

Al

2

S3Slide71

Independent Practice

Practice makes Perfect

85%Slide72

Closing

What is the empirical formula?

How

do you compose the empirical formula?Slide73

Warm Up:

4

Minutes

Write the Learning Target

You should be working SILENTLY

Stay in your own seat

Log into your computerGo to m.socrative.com

Enter room number: 230538Finish all questionsWhen you are finished, check your grades on PS ConnectSlide74

Agenda

Warm Up

[6

minutes]Notes/Examples [11 minutes]Guided Practice

[9 minutes]Quiz [20 minutes]Closing

[1 Minute]Slide75

Goal For Today

Empirical Formula:

CH

4O

Molar Mass of Molecular Formula: 96 g/mol

Student Given:Student Answer:Molecular Formula:

C3H12O3Slide76

Molecular

Formulas

Molecular

formula of

glucose

=

C6H12O6

Shows exactly how many of each atom is in a compound (unsimplified formula)Slide77

Check Point #1

Is CH

2

an empirical or a molecular formula?EmpiricalSlide78

Check Point #2

Is S

3

O6 an empirical or a molecular formula?

Molecular(Empirical Formula is SO2)Slide79

Example 1:

What is the molecular formula if the empirical formula is CH

4

O and the mass of the whole molecule is 96 g/mol?Slide80

Step 1: Find the Mass of the Empirical Formula

Step 2: Divide the mass of the Molecular Formula by the mass of the Empirical Formula

Empirical Formula:

CH4

O Mass of Molecular Formula: 96 g/mol

How to Compose the Molecular Formula?Slide81

Step 3: Multiply the

subscripts in the

empirical formula by the

answer from step 2. Empirical Formula:

CH4O Mass of Molecular Formula: 96 g/mol

How to Compose the Molecular Formula?Slide82

Example 2:

Compose the

molecular formula of the compound whose molar mass is 60.0

g/mol and empirical formula is CH4N. Slide83

Guided Practice

Teacher:

1. Will show the problem on the board

Students:Take 22 seconds to

identify the elements involved. Take 68 seconds to solve the problem with your shoulder partner

Be ready to share when Mr. Ghosh says SWAGSlide84

Guided Practice 1:

Compose the molecular formula of the compound whose molar mass is 90 g/

mol

and empirical formula is CH2O.

C3

H6O3Slide85

Guided Practice

2

:

Compose the molecular formula of the compound whose molar mass is 62 g/mol and empirical formula is CH3O.

C

2H6O2Slide86

Independent Practice

Practice makes Perfect

85%Slide87

Material Covered on Quiz

Mole Calculations (1 and 2 step)

Percent Composition

Empirical FormulasSlide88

Goal

To demonstrate mastery, we are shooting for

85%Slide89

Check Point

What is your goal for this

quiz

?

85%Slide90

Expectations for Quiz

Clear your desk of everything except a....

Writing Utensil

Calculator

Periodic Table is provided to youSlide91

Expectations

Students will keep eyes on own paper

Cheating will result in an automatic

ZEROStudents will remain SILENT for the duration of the quizSlide92

Good Luck!!Slide93

Closing

How was your quiz?

What topics do you feel you still need review on?