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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?