week 22 chemistry
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Week 22 Chemistry. Percent Composition, Empirical Formulas, Molecular Formulas. Record your Learning Target. Warm Up: 3 Minutes. Stay in your own seat. You should be working SILENTLY. - PowerPoint PPT PresentationTRANSCRIPT
Percent Composition, Empirical Formulas, Molecular Formulas
Week 22 Chemistry
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 OneNote
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]
Bubble Gum Lab
Problem
What percentage of Double Bubble Gum is composed of sugar?
Pre-Lab QuestionAccording 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?
%𝑆𝑢𝑔𝑎𝑟=𝑀𝑎𝑠𝑠𝑜𝑓 𝑆𝑢𝑔𝑎𝑟𝑀𝑎𝑠𝑠𝑜𝑓 𝐺𝑢𝑚
𝑥100 %
Lab Expectations
Work in assigned groups Raise your hand if you have a question No gum should be left on the desks
General information: How to do the lab1. Find the mass of your piece of gum before
chewing (include the wrapper)
2. Chew your gum for ~5 minutes
3. Find the mass of your piece of gum after chewing
Gum should be placed in wrapper before putting it on mass balance
4. Complete analysis and post-lab questions
Bubble Gum Lab
You each need One Piece of Gum and your Brain
Good Luck!!!
15 Minutes
Answer KeyAs Mr. Ghosh goes through the answers, highlight the ones you got wrong1. A
2. C
3. A
4. D
5. D
6. C
7. A
8. D
9. C
10. B
11. B
12. B
13. B
14. A
15. C
16. A
17. C
18. A
19. A
20. B
21. C
Class Averages (and Top Scores)
Period Top Score Class Average
1 95% 60%
3 100% 70%
4 90% 79%
5 90% 71%
6 100% 66%
7 95% 64%
What does Tracking Look Like?
Objectives
Questions on the
Exam
Your Points
Total Points
Percent Mastery
Bar Graph
Mastery85% or
Chem.7C Lewis Dot Structure
s
What does Tracking Look Like?
Objectives
Questions on the
Exam
Your Points
Total Points
Percent Mastery
Bar Graph
Mastery85% or
Chem.7C Lewis Dot Structure
s
1-5
What does Tracking Look Like?
Objectives
Questions on the
Exam
Your Points
Total Points
Percent Mastery
Bar Graph
Mastery85% or
Chem.7C Lewis Dot Structure
s
1-5 ???
[3 if you got 3
out of 5 correct]
What does Tracking Look Like?
Objectives
Questions on the
Exam
Your Points
Total Points
Percent Mastery
Bar Graph
Mastery85% or
Chem.7C Lewis Dot Structure
s
1-5 ???
[3 if you got 3
out of 5 correct]
5
What does Tracking Look Like?
Objectives
Questions on the
Exam
Your Points
Total Points
Percent Mastery
Bar Graph
Mastery85% or
Chem.7C Lewis Dot Structure
s
1-5 ???
[3 if you got 3
out of 5 correct]
5 Your points x100 Total points
Percent MasteryCathy received 1 point out
of 4
possible points. What is
her percent mastery?
Your points x100 Total points
25%
What does Tracking Look Like?
Objectives
Questions on the
Exam
Your Points
Total Points
Percent Mastery
Bar Graph
Mastery85% or
Chem.7C Lewis Dot Structure
s
1-5 ???
[3 if you got 3
out of 5 correct]
5 Your points x100 Total points
Shade in your % mastery
Your Turn
1. Go to shschem.weebly.com (our class website)
2. Hover over my page:Mr. Ghosh Homework Assignments ESL (or regular)
Chemistry
3. Under Homework Assignments, there is a new one labeled “Unit 5 Tracking”
4. Download (and save) this and fill it out
Closing
Explain the purpose of today’s lab
Warm Up: 4 Minutes
You should be working SILENTLY
Stay in your own seat
1.Log into your computer2.Go to m.socrative.com3.Enter room number: 2305384.Finish all questions
When you are finished, check your grades on PS Connect
Agenda
Warm Up [7 minutes] Notes/Examples [15 minutes] Guided Practice [12 minutes] Independent Practice [15 minutes] Closing [3 Minutes]
What is % Composition??
Percent by mass of eachelement in a compound
What is % Composition??
% compositionby mass=Massof partMass of Whole
x100 %
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?
Example 2:
What is the percent composition by mass of the elements in the compound, AgNO3?
Guided Practice
Teacher:
1. Will show the problem on the board Students:
1. Take 24 seconds to identify your given and unknown.
2. Take 46 seconds to speak with your shoulder partner about the problem
3. Be ready to share when Mr. Ghosh says SWAG
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 % N
Guided Practice 2:
What is the percent composition by mass of the elements in Mercury (II) Oxide?
92.6% Hg7.4% O
Guided Practice 3:
What is the percent composition by mass of the elements in K2CO3?
56.6% K8.7% C
34.7% O
Independent Practice
Take some time to practice finding the %
composition of the following compounds
Practice makes Perfect
85%
Closing
How do you find the percent composition of an element in a compound?
Warm Up: 4 MinutesWrite the Learning
Target
You should be working SILENTLY
Stay in your own seat
1.Log into your computer2.Go to m.socrative.com3.Enter room number: 2305384.Finish all questions
When you are finished, check your grades on PS Connect
Agenda
Warm Up [7 minutes] Notes/Examples [15 minutes] Guided Practice [12 minutes] Independent Practice [15 minutes] Closing [3 Minutes]
Goal For Today
Percent Composition:
79.8% C, 20.2% H
Student Given: Student Answer:
CH3
Empirical Formulas
empirical formula of glucose = CH2O
Shows the lowest number ratio of atoms in a compound
Example 1:
What is the empirical formula for a chemical compound that is 79.8% C and 20.2% H?
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?
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?
Example 2:
What is the empirical formula for a compound that is 81.7% Be and 18.3% H?
Guided Practice
Teacher:
1. Will show the problem on the board Students:
1. Take 22 seconds to identify the elements involved.
2. Take 68 seconds to solve the problem with your shoulder partner
3. Be ready to share when Mr. Ghosh says SWAG
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?
HgSO4
Guided Practice 2:
What is the Empirical Formula of a
compound that is 88.2 % Oxygen and
11.8% Hydrogen by mass?
H2O
Guided Practice 3:
What is the empirical formula of a
compound that is made from 50%
Cesium and 50% Iodine by mass?
CsI
Independent Practice
Practice makes Perfect
85%
Closing
What is the empirical formula?
How do you compose the empirical formula?
Warm Up: 4 Minutes
You should be working SILENTLY
Stay in your own seat
1.Log into your computer2.Go to m.socrative.com3.Enter room number: 2305384.Finish all questions
When you are finished, check your grades on PS Connect
Agenda
Warm Up [7 minutes] Notes/Examples [15 minutes] Guided Practice [12 minutes] Independent Practice [15 minutes] Closing [3 Minutes]
More Empirical Formulas!!
Writing Empirical FormulasMost 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?
Example 1:
What is the empirical formula for a chemical compound that is 49.1% Be and 50.9% N?
Common Decimals/Fractions
When we find a mole ratio that ends up close to a common decimal/fraction:
X.33X.66
X.75X.5X.25
We must multiply these ratio values by a specific number
Mole Ratio Multiply all mole ratios by
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3X.66
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3X.66 3
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3X.66 3X.75
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3X.66 3X.75 4
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3X.66 3X.75 4X.25
Table of Common Decimals/Fractions
Mole Ratio Multiply all mole ratios by
X.5 2X.33 3X.66 3X.75 4X.25 4
Table of Common Decimals/Fractions
Example 1:
What is the empirical formula for a chemical compound that is 49.1% Be and 50.9% N?
Example 2:
What is the empirical formula of a compound that is 25.9% Nitrogen and 74.1 % Oxygen by mass?
Guided Practice
Teacher:
1. Will show the problem on the board Students:
1. Take 22 seconds to identify the elements involved.
2. Take 68 seconds to solve the problem with your shoulder partner
3. Be ready to share when Mr. Ghosh says SWAG
Guided Practice 1:
What is the Empirical Formula of a
compound that is 25.9% P and 74.1% Cl?
P2Cl5
Guided Practice 2:
What is the Empirical Formula of a compound that is 17.4% Nitrogen and 82.6% Fluorine?
N2F7
Guided Practice 3:
What is the Empirical Formula of a compound that is made from 35.9% Aluminum and 64.1% Sulfur?
Al2S3
Independent Practice
Practice makes Perfect
85%
Closing
What is the empirical formula?
How do you compose the empirical formula?
Warm Up: 4 MinutesWrite the Learning
Target
You should be working SILENTLY
Stay in your own seat
1.Log into your computer2.Go to m.socrative.com3.Enter room number: 2305384.Finish all questions
When you are finished, check your grades on PS Connect
Agenda
Warm Up [6 minutes] Notes/Examples [11 minutes] Guided Practice [9 minutes] Quiz [20 minutes] Closing [1 Minute]
Goal For Today
Empirical Formula:
CH4O
Molar Mass of Molecular
Formula: 96 g/mol
Student Given: Student Answer:
Molecular Formula:
C3H12O3
Molecular Formulas
Molecular formula of glucose = C6H12O6
Shows exactly how many of each atom is in a compound
(unsimplified formula)
Check Point #1
Is CH2 an empirical or a molecular formula?
Empirical
Check Point #2
Is S3O6 an empirical or a molecular formula?
Molecular(Empirical Formula is SO2)
Example 1:
What is the molecular formula if the empirical formula is CH4O and the mass of the whole molecule is 96 g/mol?
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: CH4O
Mass of Molecular Formula: 96
g/mol
How to Compose the Molecular Formula?
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?
Example 2:
Compose the molecular formula of the compound whose molar mass is 60.0 g/mol and empirical formula is CH4N.
Guided Practice
Teacher:
1. Will show the problem on the board Students:
1. Take 22 seconds to identify the elements involved.
2. Take 68 seconds to solve the problem with your shoulder partner
3. Be ready to share when Mr. Ghosh says SWAG
Guided Practice 1:
Compose the molecular formula of the compound whose molar mass is 90 g/mol and empirical formula is CH2O.
C3H6O3
Guided Practice 2:
Compose the molecular formula of the compound whose molar mass is 62 g/mol and empirical formula is CH3O.
C2H6O2
Independent Practice
Practice makes Perfect
85%
Material Covered on Quiz
Mole Calculations (1 and 2 step)Percent CompositionEmpirical Formulas
Goal
To demonstrate mastery, we are shooting for
85%
Check Point
What is your goal for this quiz?
85%
Expectations for Quiz
Clear your desk of everything except a....
1. Writing Utensil
2. Calculator
Periodic Table is provided to you
Expectations
Students will keep eyes on own paper
Cheating will result in an automatic ZERO Students will remain SILENT for the duration of the
quiz
Good Luck!!
Closing
How was your quiz?
What topics do you feel you still need review on?