PRE-CHEM CH. 2The nature of matter

PRE-CHEM CHAPTER 2 LO Differentiate between an element, compound, and mixture

Determine if a change is chemical or physical

Correlate between changes of state and energy

Explain the law of conservation of mass for an equation

Understand and apply the importance of density

WHAT IS CHEMISTRY?What we think we know What we want to know

WHAT IS MATTER EXACTLY? Matter

Atoms are matter Elements Atom Compound Molecule Chemical formula

EXAMPLES OF CHEMICAL FORMULAS C6H12O6

H2O

Fe2O3

If I were to put a 2 in front of C6H12O6 making it 2C6H12O6 how many of each element would I then have?

3H2O

45Fe2O3

PURE SUBSTANCES AND MIXTURES Pure substance

Cannot be broken down by physical actions Elements Compounds

Mixture Can be separated

Homogeneous Heterogenous Miscible immiscible

EXAMPLES: ELEMENT, COMPOUND,

MIXTURE? Copper

Water

Wet pancake mix

Carbon dioxide

Salad

Air

GASES AND LIQUIDS Soda

Meringue pie

MATTER AND ENERGY Kinetic theory

All matter is made of atoms and molecules that act like tiny particles These tiny particles are always in motion The higher the temperature the faster they move At the same temperature the more massive particles move slower than less

massive particles

viscosity

ENERGY Evaporation

Condensation

Sublimation

Mrzimmerman.org

LAWS OF CONSERVATION Law of conservation of mass

Law of conservation of energy

ARE THE FOLLOWING EQUATIONS BALANCED?

4P + 5O2 P4O10 (Yes) 14 Atoms on each side

KClO3 KCl + O2 (No) 5 and 4

H2 + O2 H2O (No) 4 and 3

2Na + Cl2 2NaCl (Yes) 4 Atoms on each side

S8 + O2 SO3 (No) 10 and 4

ON YOUR OWN, ARE THE FOLLOWING BALANCED?

2Al + 3FeO Al2O3 + 3Fe

6CO2 + 6H2O C6H12O6 + 6O2

2H3PO4 H4P2O7 + H2O

CHEMICAL AND PHYSICAL CHANGESChemical changes/property

reactivity

Chemical composition changes

Physical changes/property

Melting and boiling point

Density

Buoyancy

EXAMPLES OF PHYSICAL AND CHEMICAL CHANGES

Digesting food

Ripping paper up

A car exploding

Boiling water

Dissolving sugar in water

Cutting up watermelon

Baking a cake

DENSITY What exactly is dentistry?

Write down on your handout what you believe density is and then discuss it with the person sitting next to you.

DENSITY g/mL or g/cm3

same bc mL is volume and v=l x w x h (cm x cm x cm)

D=m/v

M=vD

V=M/D

DENSITY EXAMPLES What is the density of carbon dioxide gas if 0.196 g occupies a volume of

100 mL?g.

A block of wood 3.0 cm on each side has a mass of 27 g. What is the density of this block?

CON’T An irregularly shaped stone was lowered into a graduated cylinder holding

a volume of water equa to 2.0 mL. The height of the water rose to 7.0 mL. If the mass of the stone was 25 g, what was its density?

Incorrect numbers, but an example.

Five mL of ethanol has a mass of 3.9g and 5.0 mL of benzene has a mass of 4.4 g. Which liquid is more dense?

The density of silver is 10.5 g/mL. What will be the volume of apiece of sliver with a mass of 42.0 g?

An object has a density of 54.76 g/mL and a volume of 3.40 mL. What is the mass?

A piece of metal has the mass of 42.07g and a density of 5.3 g/cm3. What is the volume of this metal?