1. Conservation of mass
9/15/15

2. Brain Teaser Girls Like, Boys Use
What 8-letter word describes something girls like, boys use and parents are afraid of yet remember fondly?
Hint: It has these letters: macroen

3. Review – Bell Ringer
Classify the images according to their state of matter 4.

4. Evidence of a physical change
A chemical reaction always produces a change in properties
Color change
Formation of a gas
Burning of wood (releases heat - energy)
Smell changes (odor)
Temperature changes

5. The Law of Conservation of mass or matter (don’t write this yet)
Why is it a law and not a theory?
After scientists started measuring the mass before and after chemical reactions, they noticed that the total mass involved in the reaction stayed the same (took hundreds of years of data to see that the observation was consistent every time!)
Is it an explanation?
No, its an observation! Therefore it is a law!

6. The Law
The law of conservation of mass states that mass is neither created or destroyed in any process – it is conserved.
Mass of reactants = mass of products
MassR = MassP

7. Mass is conserved in physical and chemical changes!
Weigh a piece of paper
tear it and weigh both pieces = same mass as before
Weigh a piece of aluminum foil
crumple it into a ball = same mass as before
Combine carbon and oxygen to get carbon dioxide (what we breathe out) = same mass as before
carbon + oxygen  carbon dioxide reactants products
C O2  CO2

8. Conservation of mass videos
Conservation videos
(Block 4 –Todd Ramsey)
Chemical reaction conservation demo: (B1 & B4 – Mr. King)
Phase change conservation demo (:

9. (I do) practice From your homework:
178.8g H2O (liq) g H (gas) + ____ g O (gas)
Whole is 178.8g
2 parts make up the whole (Hydrogen and Oxygen)
If we know 1 part of the whole, we can calculate the other part of the whole!
178.8 = 20 – x
178.8 – 20 = x
158.8 = x = 159 g (3 SF)
You just did a basic conservation of mass problem! 

10. (We Do) Practice
If Mercury (II) oxide is what is produced when mercury and oxygen are combined, what is the mass of the reactant oxygen when combined with 9.26 g of liquid mercury to produce g of Mercury (II) oxide?
9.26 g (liq) Hg + _____ O = g Hg2O2
x = 10.00
x = – 9.26 = 0.74
0.74 g O

11. (You Do) Practice
A 28.0 g sample of nitrogen gas combines completely with 6.0 g of hydrogen gas to form ammonia. What is the mass of the ammonia formed?
28.0 g g = 34 g of ammonia

12. Practice with your partner ( 7 minutes)
Page 65
# 12
A & B

13. Pg 65 # 12 A 22.99 g Na + 35.45 g Cl = _____ NaCl
= g NaCl

14. Pg. 65 # 12 B
12.2 g X + ____ Y = 78.9 g XY
x = 78.9
X = 78.9 – 12.2 = 66.7 g Y

15. Review
The law of conservation of mass states that mass is neither ________ or ________ in any process – it is _________.
Mass of Reactants = _________________
Be prepared to work some problems tomorrow as a review! 
created
destroyed
conserved
Mass of Products

16. Pure substances (homogeneous)
Types of Matter
Pure substances (homogeneous)
Elements
Compounds
Mixtures (homogeneous or heterogeneous)

17. Pure Substances Matter that is uniform and unchanging in composition
Salt and water
But NOT ocean water

18. Elements Simplest type of matter - one type of atom (homogeneous)
Elements arranged according to increasing atomic mass and recurring properties in PERIODIC TABLE OF THE ELEMENTS
Each element has unique one or two letter symbol

19. Elements
91 elements occur naturally
Example: Copper (Cu)

20. Element Each element has a unique chemical name and symbol.
The first letter is always capitalized and the remaining letters are lowercase.
Ex:
C – Carbon
Cu – Copper
Cs – Cesium
Cr – Chromium
Co - Cobalt

21. Diatomic molecules Two kinds of atoms
Molecules composed of only two atoms of either the same or different chemical elements.
H2, N2, O2, F2, Cl2, Br2, I2

22. Element Classification
groups or families
periods
properties
metals
nonmetals
metalloids
Noble gases
main block

23. Pure substances Compounds Salt (always composed of Na and Cl)
Water (always composed of H and O)

24. Compounds Chemical combinations of two or more elements
Most familiar substances are compounds
Can be broken down into simpler substances by chemical reactions.

25. Compounds Table salt isn’t an element!
It’s a compound (a substance composed of atoms of two or more different elements that are chemically combined)
EX: NaCl
They combine ONLY when the compound is more stable than the individual atoms.
Substances go through a chemical change to form a compound, and the different elements seem to lose their individual characteristics.
Na (explosive alone) + Cl (poisonous gas alone) = NaCl (safe to eat when bonded together)

26. Law of definite proportions
Elements that make up compounds combine in definite proportions by mass.
Percent by mass (%) = Mass of element x 100
Mass of compound

27. Example 500.0 g of sucrose isolated from a sample of sugar cane
Sucrose has C, H, O
What is the percent by mass of carbon in the sucrose molecule if the mass is g C?
210.5 g C x 100 = % Carbon
500.0 g Sucrose

28. Example 500.0 g of sucrose isolated from a sample of sugar cane
Sucrose has C, H, O
What is the percent by mass of Hydrogen in the sucrose molecule if the mass is 32.4 g H?
32.4 g H x 100 = 6.48 % Hydrogen
500.0 g Sucrose

29. Example 500.0 g of sucrose isolated from a sample of sugar cane
Sucrose has C, H, O
What is the percent by mass of Oxygen in the sucrose molecule if the mass is g O?
257.1 g O x 100 = 51.4 % Oxygen
500.0 g Sucrose

30. You try Pg

31. Mixtures (heterogeneous)

32. Remember that compounds are when elements combine with other elements through CHEMICAL BONDING!
Covalent bonding
Ionic Bonding
Example: A baked cake, table salt, water molecules
Compound

33. Mixture Elements are NOT BONDING CHEMICALLY in mixtures.
They just mix together, retaining their original properties.
They can be physically separated after they are combined.
Examples:
A salad in a bowl where the different vegetables can be put together in a bowl, but can be easily separated.
The blue sand and salt we combined in lab.
Salt dissolved in water. Can pour the mixture through a filter and remove the salt from the water.

34. Homogeneous Mixtures
two or more kinds of matter with uniform composition
air, vinegar, salt water, and Sprite
liquid homogeneous mixtures - SOLUTIONS
solid homogeneous mixtures of metals - ALLOYS

35. Heterogeneous Mixtures
combination of two or more kinds of matter with different parts or properties; composition is NOT uniform
blood, whole milk, granite, and chocolate chip cookies

36. Separation of Matter Elements – cannot be broken down
Compounds – can be broken down by chemical methods
Mixtures – can be separated by physical means
Separation depends on properties of the matter

37. Separation Techniques
Distillation
Chromatography
Density
Centrifuge
Filtration

39. Classification of Matter
page 11

40. Pure Substances one kind of atom or molecule uniform composition
Elements –one kind of atom
Compounds – one kind of molecule
Elements: aluminum, gold, carbon
Compounds: salt, baking soda, water

41. Matter and Its Properties