happy tuesday! copy down tonight’s homework

While I take attendance and check homework:Start a new page of notes:11/13Obj: Explain the Law of Conservation of Mass

Write these equations:2NaHCO3 + CaCl2 →CaCO3+ 2NaCl + H2O + CO2

4Fe + 3O2 → 2Fe2O3

substance mixed with water mixed with vinegar mixed with iodine

baking soda

cornstarch

powdered sugar

baking powder

granulated sugar


baking soda bubbles (gas)

cornstarch

powdered sugar

baking powder

granulated sugar


baking soda no bubbles bubbles (gas)

cornstarch

powdered sugar

baking powder

granulated sugar


baking soda no bubbles bubbles (gas) no bubbles

cornstarch

powdered sugar

baking powder

granulated sugar



cornstarch

powdered sugar

baking powder bubbles (gas)

granulated sugar



cornstarch

powdered sugar

baking powder bubbles (gas) bubbles (gas)

granulated sugar



cornstarch

powdered sugar

baking powder bubbles (gas) bubbles (gas) bubbles (gas)

granulated sugar



cornstarch no bubbles no bubbles no bubbles

powdered sugar no bubbles no bubbles no bubbles


granulated sugar no bubbles no bubbles no bubbles



cornstarch no bubbles no bubbles no bubblesturned black

powdered sugar no bubbles no bubbles no bubbles






powdered sugar no bubbles no bubbles no bubblesturned black






powdered sugar no bubbles no bubbles no bubblesturned black

baking powder bubbles (gas) bubbles (gas) bubbles (gas)turned black


PROOF THAT A CHEMICAL CHANGE HAS HAPPENED:

Show that a new substance has been formed.

CLUES THAT SUGGEST A CHEMICAL CHANGE HAS PROBABLY

HAPPENED:Production of a gas, unexpected change

in color or temperature

Reaction #1 – ziploc bag experiment

2NaHCO3 + CaCl2 →CaCO3+ 2NaCl + H2O + CO2

“mass” 2NaHCO3 + CaCl2 = 165.7g“mass” CaCO3,2NaCl ,H2O,CO2 =165.7g

Lego equation:

2(PYBG3) + WR2 →WBG3+ 2(PR)+ Y2G + BG2

Reaction #2 – rusting reaction

4Fe + 3O2 → 2Fe2O3

“mass” 4Fe + 3O2 =“mass” 2Fe2O3 =

Lego equation:

4B + 3(Y2)→ 2(B2Y3)

LAW OF CONSERVATION OF MASS

In a chemical reaction, atoms are not created, destroyed, or turned into

other kinds of atoms.

The bonds that connect atoms together are broken and rearranged to

make new substances.

Before you leave...

Tell me everything you can about the possible products of a chemical reaction involving this awesome compound

MATTER PURE SUBSTANCES MIXTURES PROPERTIES DENSITY

10 10 10 10 10

20 20 20 20 20

30 30 30 30 30

40 40 40 40 40

50 50 50 50 50

Question 1 – 10 (#1)

• All matter is either a ____ or a _______

Answer 1 – 10

• pure substance or a mixture


• All mixtures are either ________ or ________

Answer 1 – 20

• homogeneous or heterogeneous


• All pure substances are either _________ or _____________.

Answer 1 – 30

• elements or compounds


• What is the difference between a pure substance and a mixture?

•

Answer 1 – 40

• A pure substance has only one kind of particle (one “ingredient”). Every group of atoms is exactly the same.

• A mixture has more than one kind of particle (more than one “ingredient”). There are different kinds of groups.

Question 1 – 50 (#8)• identify the following substances as elements,

compounds, homogeneous mixtures, or heterogeneous mixtures:

• sugar dissolved in water * pure water• carbon dioxide * air• oxygen * fog in air• chocolate milk * baking soda• plain milk• a slug

Answer 1 – 50 • sugar dissolved in water homogeneous mixture• carbon dioxide compound• oxygen element• chocolate milk hetero-/homogeneous mixture• plain milk homogeneous mixture• a slug heterogeneous mixture• pure water compound• air homogeneous mixture• fog in air heterogeneous mixture• baking soda compound


• What is the difference between an element and a compound?

Answer 2 – 10

• All of the atoms in a sample of an element are exactly the same.

• There are different kinds of atoms in a sample of a compound, but all of the groups of atoms are the same.

Question 2 – 20 (not on the study guide)

• Both compounds and mixtures have different kinds of atoms. What is the difference between a compound and a mixture?

Answer 2 – 20

• Since a compound is a pure substance, all of the particles (groups of atoms) are the same, even though there are different kinds of atoms.

• In a mixture, there are different kinds of particles (groups of atoms).

Question 2 – 30 (#13)• How many atoms of each element is present in one

molecule/particle of the following compounds?

• N2

• H2SO4

• NaF• CaCO3

• LiOH• NH4NO3

Answer 2 – 30

• N2 - 2 atoms of nitrogen

• H2SO4 – 2 atoms of hydrogen, 1 sulfur, 4 oxygen

• NaF – one atom of sodium, one atom of fluorine• CaCO3 – one atom of calcium, 1 carbon, 3 oxygen

• LiOH – 1 atom of lithium, 1 oxygen, 1 hydrogen• NH4NO3 – 2 nitrogen, 4 hydrogen, 3 oxygen

Question 2 – 40 (#21)

• When the mitochondria in your cells produce energy, they carry out the following chemical reaction:

• glucose + oxygen ---> carbon dioxide + water• On the left side of the equation, there are 6

carbons, 12 hydrogens, and 18 oxygens.• What does the Law of Conservation of Mass tell

you about the atoms on the right side of the equation?

Answer 2 – 40

• There are 6 carbons, 12 hydrogens, and 18 oxygens. Whatever atoms go in to the reaction, the same atoms come out of the reaction.

Question 2 – 50 (#22)

• What happens to the atoms when substances undergo chemical changes?

Answer 2 – 50

• The atoms themselves are not changed – atoms are not created, destroyed, or changed into different atoms.

• The arrangement of the atoms changes to make new substances. Chemical bonds between atoms are broken and re-formed in new ways.


• Solutions are ___________________ mixtures.

Answer 3 – 10

• homogeneous

Question 3 – 20 (#7)How can you tell if a mixture is

homogeneous or heterogeneous?

Answer 3 – 20

A homogeneous mixture looks the same everywhere. It is well-blended.

You can see different things in a heterogeneous mixture – the “ingredients” are not well-blended.

Question 3 – 30 (not on study guide)

• You have a container that has matter that is made up of hydrogen and oxygen atoms. Does it have to be water?

Answer 3 – 30

• No, it doesn’t have to be water. It could be:– Water…– A mixture of water plus oxygen gas– A mixture of water plus hydrogen gas– A mixture of water plus oxygen gas and hydrogen

gas– Hydrogen peroxide– A mixture of hydrogen peroxide plus water, etc.

Question 3 – 40 (#23)

• Name one pure substance, one heterogeneous mixture, and one homogeneous mixture from your recipe.

Answer 3 – 40

• Various answers


• When a mixture undergoes a chemical change, what ALWAYS happens?

Answer 3 – 50

• At least one new substance is formed

Question 4 – 10 (#10)

• What is meant by “gold is denser than aluminum”?

Answer 4 – 10

The particles in a sample of gold are more tightly packed than the particles in a sample of aluminum.

There is more matter in a cubic centimeter of gold than in a cubic centimeter of aluminum.

Question 4 – 20 (#11)

• You have two plastic toys. Mr. Froggy occupies 200 cm3 of space and is 150 grams. Miss Squidly is 300 grams and occupies 200 cm3 of space. Will either of your toys float in the bathtub?

Answer 4 – 20

• Mr. Froggy will float. His density is less than 1g/mL.

• density=mass/volume=150g/200cm3

=0.75 g/cm3

Miss Squidly will not float, because her density is 1.5 g/cm3

Question 4 – 30 (#12)

• You have 500 mL of two different liquids. The red liquid has a mass of 500 g. The green liquid has a mass of 250 g. If you wanted to layer one on top of the other, which order will work?

Answer 4 – 30

• The green liquid is less dense than the red liquid, so it will layer on top.

• green=250g/500mL = 0.5 g/mL• red=500g/500mL = 1.0 g/mL


• When liquid water becomes a gas, its density changes.

–Does its density go up or go down?

–Is this a chemical change?

Answer 4 – 40

• Its density decreases.

• No, this is just a physical change. It is still water (H2O)

Question 4 - 50

• When liquid water freezes, its density changes.

–Does its density go up or down?

–Is this a chemical change?

Answer 4 – 50

• Its density decreases. Ice floats on liquid water.

• No, it’s just a physical change. It is still water (H2O).

Question 5 – 10 (#9 and 15)

• List 5 different physical properties of this piece of paper.

Answer 5 – 10

• 28 cm long, 21.5 cm wide, 2 grams, density 0.3 g/mL, white, black writing, rectangular, thin, translucent, smooth, not magnetic

Question 5 – 20 (#14)

• What is the difference between physical properties and chemical properties?

Answer 5 – 20

• You can observe or measure a physical property without changing the object into something new.

• To demonstrate a chemical property, you must change the substance into something new?

Question 5 – 30 (#16 and 18)

• What happens to the identity of a substance when it undergoes a physical change?

• What happens to the identity of a substance when it undergoes a chemical change?

Answer 5 – 30 • When something undergoes a physical

change, it is still the same substance. Its identity doesn’t change. (Ice is still water, for example)

• When something undergoes a chemical change, it becomes something new. Its identity changes. (Wood becomes ashes, when it burns)

Question 5 – 40 (#20)

• What are some clues that a chemical change has occurred?

Answer 5 – 40

• unexpected change in color, temperature, or state of matter (production of gas, for example); production of a new smell

Question 5 – 50 (#19)

• Why is flammability a chemical property?

Answer 5 – 50

• To demonstrate that something is flammable, you must change it into something different.

Before you leave…

• Do you think you will be able to bring in food from your recipe next Wednesday?

• What food will you be bringing?

happy tuesday! copy down tonight’s homework

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