matter & change chapter 2. a. describing matter understanding matter begins with observation...
Post on 27-Mar-2015
220 Views
Preview:
TRANSCRIPT
Matter & ChangeMatter & ChangeChapter 2
A. Describing MatterA. Describing Matter
Understanding matter begins with observation
Matter is anything that has mass and takes up space
Chemistry – the study of matter and the changes it undergoes
B. Four States of MatterB. Four States of Matter
Solidsparticles vibrate but can’t move
aroundfixed shape fixed volumeVirtually incompressible
B. Four States of MatterB. Four States of Matter
Liquidsparticles can move
around but are still close together
variable shapefixed volumeVirtually incompressible
B. Four States of MatterB. Four States of Matter
Gasesparticles can separate and
move throughout containervariable shapevariable volumeEasily compressedVapor =
gaseous state of a substance that is a liquid or solid at room temperature
B. Four States of MatterB. Four States of Matter
Plasmaparticles collide with enough energy
to break into charged particles (+/-)gas-like, variable
shape & volumestars, fluorescent
light bulbs, TV tubes
II. Properties & Changes in MatterExtensive vs. Intensive
Physical vs. Chemical
A. Physical PropertiesA. Physical Properties
Physical Propertycan be observed without changing the
identity of the substance
B. Physical PropertiesB. Physical Properties
Physical properties can be described as one of 2 types:
Extensive Propertydepends on the amount of matter
present (example: length)
Intensive Propertydepends on the identity of substance, not the amount (example: scent)
C. Extensive vs. IntensiveC. Extensive vs. Intensive
Examples:boiling point
volume
mass
density
conductivity
intensive
extensive
extensive
intensive
intensive
D. Physical ChangesD. Physical Changes
Physical Changechanges the form of a substance without
changing its identity
properties remain the same
Examples: cutting a sheet of paper, breaking a crystal, all phase changes
D. Phase Changes – PhysicalD. Phase Changes – Physical
Evaporation =
Condensation =
Melting =
Freezing =
Sublimation =
Liquid -> Gas
Gas -> Liquid
Solid -> Liquid
Liquid -> Solid
Solid -> Gas
E. Chemical PropertiesE. Chemical Properties
Chemical Propertydescribes the ability of a substance to
undergo changes in identity
F. Physical vs. Chemical PropertiesF. Physical vs. Chemical Properties
Examples:melting point
flammable
density
magnetic
tarnishes in air
physical
chemical
physical
physical
chemical
G. Chemical ChangesG. Chemical Changes
Process that involves one or more substances changing into a new substanceCommonly referred to as a chemical
reactionNew substances have different
compositions and properties from original substances
G. Chemical ChangesG. Chemical Changes
Signs of a Chemical Changechange in color or odor
formation of a gas
formation of a precipitate (solid)
change in light or heat
H. Physical vs. Chemical ChangesH. Physical vs. Chemical Changes
Examples:rusting iron
dissolving in water
burning a log
melting ice
grinding spices
chemical
physical
chemical
physical
physical
What Type of Change?What Type of Change?
What Type of Change?What Type of Change?
I. Law of Conservation of MassI. Law of Conservation of Mass
Although chemical changes occur, mass is neither created nor destroyed in a chemical reaction
Mass of reactants equals mass of products
massreactants = massproducts
A + B C
III. Classification of Matter (pp. 80-87)Matter FlowchartPure SubstancesMixtures
A. Matter FlowchartA. Matter Flowchart
MATTER
Can it be physically separated?
Homogeneous Mixture
(solution)
Heterogeneous Mixture Compound Element
MIXTURE PURE SUBSTANCE
yes no
Can it be chemically decomposed?
noyesIs the composition uniform?
noyes
A. Matter FlowchartA. Matter Flowchart
Examples:graphite
pepper
sugar (sucrose)
paint
soda
element
hetero. mixture
compound
hetero. mixture
solution
B. Pure SubstancesB. Pure Substances
Elementcomposed of identical atomsEX: copper wire, aluminum foil
B. Pure SubstancesB. Pure Substances
Compoundcomposed of 2 or more
elements in a fixed ratio
properties differ from those of individual elements
EX: table salt (NaCl)
C. MixturesC. Mixtures
Variable combination of 2 or more pure substances.
Heterogeneous Homogeneous
C. MixturesC. Mixtures
Solutionhomogeneousvery small particlesparticles don’t settleEX: rubbing alcohol
C. MixturesC. Mixtures
Heterogeneousmedium-sized to
large-sized particles
particles may or may not settle
EX: milk, fresh-squeezed
lemonade
C. MixturesC. Mixtures
Examples: tea
muddy water
fog
saltwater
Italian salad dressing
Answers: Solution
Heterogeneous
Heterogeneous
Solution
Heterogeneous
III. Density FunFormulaSimple CalculationsDimensional Analysis
A. Derived UnitsA. Derived Units
Combination of base unitsVolume – length length length
1 cm3 = 1 mL 1 dm3 = 1 LDensity – mass per unit volume
(g/cm3)
D = MV D
M
V
Broken Heart
B. Density CalculationsB. Density Calculations
An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.
GIVEN:
V = 825 cm3
D = 13.6 g/cm3
M = ?
WORK:
M = DV
M = (13.6 g/cm3)(825cm3)
M = 11,220 g
M = 11,200 gDM
V
B. Density CalculationsB. Density Calculations
A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?
GIVEN:
D = 0.87 g/mL
V = ?
M = 25 g
DM
V
WORK:
V = M D
V = 25 g
0.87 g/mL
V = 28.7 mL = 29 mL
B. Density CalculationsB. Density Calculations
You have a sample with a mass of 620 g and a volume of 753 cm3. Find its density.
GIVEN:
M = 620 g
V = 753 cm3
D = ?
DM
V
WORK:
D = M V
D = 620 g
753 cm3
D = 0.82 g/cm3
C. Density Calculations with DAC. Density Calculations with DA
Used when units do not agreeConversions must be made before
using formula
D = MV
D = g
cm3
You have 3.10 pounds of gold. Find its volume in cm3 if the density of gold is 19.3 g/cm3.
lb cm3
3.10 lb 1 kg
2.2 lb= 73.0 cm3
1000 g
1 kg
1 cm3
19.3 g
C. Density Calculations with DAC. Density Calculations with DA
You have 0.500 L of water. Find its mass in ounces if the density of water is 1.00 g/cm3.
L oz0.500 L 1000 mL
1L
= 17.6 oz
1.00g
1 cm3
C. Density Calculations with C. Density Calculations with DADA
1 cm3
1 mL1 kg
1000 g16 oz
1lb
2.2 lbs
1kg
top related