1. Today’s Do Now 3(NH4)2SO3 3Sn(SO3)2 5H2SO4
List the names of the elements in each compound or molecule and how many atoms of each element exist
3(NH4)2SO3
3Sn(SO3)2
5H2SO4

2. 1. 3(NH4)2SO3 6 nitrogen atoms 24 hydrogen atoms 3 sulfur atoms
Today’s Do Now
1. 3(NH4)2SO3
6 nitrogen atoms
24 hydrogen atoms
3 sulfur atoms
9 oxygen atoms

3. Today’s Do Now
2. 3Sn(SO3)2
3 tin atoms
6 sulfur atoms
18 oxygen atoms

4. 3. 5H2SO4 10 hydrogen atoms 5 sulfur atoms 20 oxygen atoms
Today’s Do Now
3. 5H2SO4
10 hydrogen atoms
5 sulfur atoms
20 oxygen atoms

5. Law of conservation of mass

6. Today’s Game Plan 5 minutes 15 minutes 20 minutes 10 minutes
Do Now
10 minutes
Law of Conservation of Mass
15 minutes
Practice, Practice, Practice
20 minutes
Balancing Equations
Exit Ticket
5 minutes

7. By the end of today’s class period, I will be able to…
Understand and apply the law of conservation of mass

8. Quick Review

9. Law of Conservation of Mass
Matter cannot be created or destroyed in a chemical reaction
Mass Reactants = Mass Products

10. Law of Conservation of Mass
All the atoms of the reactants are still present in the products; they’ve just been rearranged
The reaction between methane and oxygen

11. Because of the Law of Conservation of Mass…
An equation must be balanced.
It must have the same number of atoms
of the same element on both sides.

12. Chemical Equations must be Balanced
4 Al(s) O2(g) Al2O3(s)
4 g Al g O2 yield 2 g Al2O3
This equation means:
4 Al atoms O2 molecules  2 molecules of Al2O3 or
4 Al moles O2 moles  2 moles of Al2O3
108 g Al g O = g Al2O3

13. Open vs. Closed Systems
Open System: reaction taking place in an open system can exchange matter with its surroundings
Closed System: reaction taking place in a closed system cannot exchange matter with its surroundings

14. Baking Soda and Vinegar
An open vs. closed system
Reactants
Products
Mass of E-flask 1 and balloon
Mass of E-flask 2

15. Write.Pair.Share
How can you explain to someone that the Law of Conservation of Mass holds true for both Erlenmeyer flasks??

16. Today’s Game Plan 5 minutes 15 minutes 20 minutes 10 minutes
Do Now
10 minutes
Law of Conservation of Mass
15 minutes
Practice, Practice, Practice
20 minutes
Balancing Equations
Exit Ticket
5 minutes

17. Let’s Get Together! Law of Conservation of Mass Problems
You will work with a different member of the class on each of the problems
Record the name of the person you worked with in the box
Done early??? Try to balance the chemical equations on the bottom of the back page

18. Today’s Game Plan 5 minutes 15 minutes 20 minutes 10 minutes
Do Now
10 minutes
Law of Conservation of Mass
15 minutes
Practice, Practice, Practice
20 minutes
Balancing Equations
Exit Ticket
5 minutes

19. By the end of the class period today I will be able to…
Use the law of conservation of mass to balance chemical equations

20. Why do we balance equations?
Chemical equations must be balanced to obey the law of conservation of mass (atoms are not created or destroyed, just rearranged)

21. How do I balance an equation?
To balance an equation, you may only change coefficients, not subscripts (changing subscripts would change the identity of the compound)

22. The ‘Best’ Balanced Equation
The ‘best’ balanced equation is the one with the smallest whole number coefficients.
2Al + 3H2SO4  Al2(SO4)3 + 3H2
Instead of
4Al + 6H2SO4  2Al2(SO4)3 + 6H2

23. Does the Equation obey the Law of Conservation of Mass?
Al + H2SO4  Al2(SO4) H2
Equation #2:
Pb(NO3)2 + H2S  PbS + HNO3

24. 4 Balancing ‘Tricks’!
1. Start with the most complicated molecule 2. You cannot change subscripts! 3. Leave individual elements until last (especially Oxygen and Hydrogen) 4. Treat polyatomic ions as though they are one entity if they appear on both sides of the equation

25. Class Example
Al + H2SO4  Al2(SO4) H2

26. Today’s Game Plan 5 minutes 15 minutes 20 minutes 10 minutes
Do Now
10 minutes
Law of Conservation of Mass
15 minutes
Practice, Practice, Practice
20 minutes
Balancing Equations
Exit Ticket
5 minutes

27. We talkin’ about Practice??
Guided Practice will assume the following cycle:
1. Two minutes to work independently
2. One minute to work with your neighbor
3. One minute for me to cold call students for different portions of the answer/how you discovered the answer.

28. You Try…
____ NaClO3  ____ NaCl + ____ O2 ___Fe(s) + ___O2(g) + ___H2O(ℓ) → ___Fe(OH)2(s)

29. ___C8H6 + __O2 → ___CO2 + ___H2O
Class Examples
___C8H6 + __O2 → ___CO2 + ___H2O

30. We talkin’ about Practice??
Guided Practice will assume the following cycle:
1. Two minutes to work independently
2. One minute to work with your neighbor
3. One minute for me to cold call students for different portions of the answer/how you discovered the answer.

31. ___C2H5OH(l) + __O2(g)  __CO2(g) + __H2O(g)
You Try…
___C2H5OH(l) + __O2(g)  __CO2(g) + __H2O(g)

32. __Sc2O3 + __Cl2 + __S2Cl2 __ScCl3 + __SOCl2
Class Examples
__Sc2O3 + __Cl2 + __S2Cl2 __ScCl3 + __SOCl2

33. Today’s Game Plan 5 minutes 15 minutes 20 minutes 10 minutes
Do Now
10 minutes
Law of Conservation of Mass
15 minutes
Practice, Practice, Practice
20 minutes
Balancing Equations
Exit Ticket
5 minutes

34. Homework: