unit 4 - matter & energy Flashcards
matter
- anything that takes up space (volume) and has mass
- matter can exist in 3 phases
at certain temp or pressure, the matter can be…
a solid, liquid, or a gas
solid phase
- orderly arrangement
- particles are in fixed positions / tightly packed
- crystalline
- particles vibrate/slight movement
- definite volume
- definite shape
all molecular movement is said to stop at
0 degrees Kelvin
properties of gas phase
- total disorder
- much Empty Space
- particles have complete freedom of motion/move fastest
- particles are far apart
- no definite volume & no definite shape
properties of liquid phase
- some disorder
- particles are free to move relative to eachother
- move faster and more than a liquid/less than gas
- definite volume
- no definite shape (indefinite, negligible = synonymous)
changes in what result in changes of phases
temperature and/or pressure
temperature affects what
how fast particles move
pressure affects what
how packed the particles are
phase changes are…
physical changes which can be endothermic or exothermic
endothermic
process that requires absorption of heat (heating process)
exothermic
process that involves the release of heat (cooling process)
melting
- Endothermic Change
(Heat is Absorbed)
● Solid (s) → Liquid (l)
Phase Change
evaporation/vaporization
- Endothermic
(Heat is Absorbed)
● Liquid (l) → Gas (g)
Phase Change
sublimation
- Endothermic
(Heat is Absorbed)
● Solid (s) → Gas (g)
● Skips the Liquid Phase
● Ex. Dry Ice & Iodine
CO2 (s) → CO2 (g)
I2 (s) → I2 (g)
condensation
- Exothermic
(Release of Heat)
● Gas (g) → Liquid (l)
Phase Change
freezing
- Exothermic
(Release of Heat)
● Liquid (l) → Solid (s)
deposition
- Exothermic
(Release of Heat)
● Gas (g) → Solid (s)
Phase Change
in chemical reactions, what is conserved
mass, charge, and energy of matter
pure substance
- a type of matter.
- has definite composition and the properties are the same throughout
Ex. Elements & Compounds (No Mixtures)
elements
- made of one kind of atom.
- all atoms that make up an element have the same atomic number.
- CAN NOT be broken down by ordinary means.
compound
- a substance made of two or more
elements that are chemically combined. - It has a definite Composition
-mass ratio (formula) never changes
binary compound
- simplest compouds
- made up of only 2 kinds of elements
properties of a compound
Properties of the compound are drastically
different from the original elements.
can a compound be broken down by ordinary chemical means
YES (decomposition)
mixture
– a combination of two or more pure substances that can be separated by physical means
- combination of two or more distinct substances
- composition ALWAYS VARIES!
- parts are only Physically combined
(aq)
- aqueous
- dissolved in water = solution
- mixture
properties of a mixture
1) Formed by a physical combination
2) Parts of a mixture retain their original properties.
3) Parts are separated by physical properties.
Ex. Magnetism, density, size, boiling point
4) Parts of a mixture are in any proportion- VARY!
- No Definite Formula; composition varies
Ex. NaCl (aq)- can be made with various amounts of water and salt.
two types of mixtures
homogeneous and heterogeneous
homogeneuos
- all parts look the same
-particles evenly distributed
Ex. Air, Milk, NaCl (aq)
heterogeneous
- you can see the parts
- particles unevenly distrib.
Ex. Rocks, Soil, & Sand
physical properties
characteristic which can be
observed without producing a new substance.
malleabilitiy
ability to be hammered into a sheet and not fall a part
ductility
ability to be drawn into a wire
conductivity
ability to carry a current or heat
tenacity
ability to resist being pulled apart
sublimation
can change from a solid to a gas without melting at certain temperature
boiling point
temperature at which liquid turns to gas
solubility
ability to dissolve
brittleness
ability to shatter when struck
magnetism
ability to be attracted to a magnet
melting point
temperature at which solid turns to a liquid
chemical properties
characteristics which describe how a substance reacts or fails to react with other substances
physical change
a change in the appearance but NOT in major properties or composition
chemical change
a change in which one or more substances form with totally new properties and compounds
ex: burning, digestion, rusting/corrosion, souring of milk, decaying
parts of a mixture can be separated based on their…
density, charge, boiling point, size, magnatism
filtration
- Is used to separate mixture components based on SIZE.
(Heterogeneous Mixture).
*Small particles (filtrate)
pass through the filter paper.
*Large particles (residue)
remains on the filter paper.
density
A separatory funnel is used
to separate parts of a mixture
based on differences in DENSITY
paper chromatography (charge/polarity)
● Separates a mixture based on
different attractions to the
paper.
- Molecules have a difference
in CHARGE/POLARITY
● Components of the mixture
move up the paper, BUT at
different rates separate from each other.
distillation (boiling point)
- Used to seprate Homogenous Mixtures based on Boiling Point
- Separation between liquids
ex: alcohol and H2O - solid dissolved in liquid
ex: NaCl dissolved in H2O
temperature
The measure of the average kinetic
energy (energy of motion) of a substance’s particles.
- measured in Fahrenheit, Celsius, and Kelvins
Heat
The amount of energy transferred from one substance to another.
- measured in units of Joules or calories
heat moves from…
a higher temp to a lower temp
boiling point of H2O
100°C & 373 K
freezing point of H2O
0°C & 273 K
body temp
37°C & 310 K
room temp
20-25°C & 293-298 K
absolute zero
temperature at which all molecular motion stops
- 0K or -273°C
to find kelvin from celcius…
°C + 273
to find celcius from kelvin
K - 273
a 1° change on the Celcius scale equals a 1° change on the Kelvin scale
heating and cooling curves
are diagrams that represent a substance being heated or cooled at a constant rate
- they illustrate melting point and boiling point
melting point
temp. at which solid and liquid phases exist in equilibrium (same as the freezing point)
boiling point
temp. at which liquid and gas phases exist in equilibrium (same as the condensation point)
kinetic energy
energy of motion; increases as temp increases
potential energy
stored energy in bonds; increases as the distance between the molecules increases
heat of fusion
amount of heat required to melt 1 gram of a substance; S -> L
heat of vaporization
amount of heat to vaporize a substance; L -> G
table s: solid
phase below its freezing or melting point
table s: liquid
phase between its freezing point and boiling point
gas
phase above its boiling point/condensation point
calorimetry
- study of heat and its measurement
- measurement of heat absorbed or released by a substance
- unit for heat (Q) is Joules
specific heat
amount of heat energy in joules required to change the temperature of 1 gram of a particular substance by 1 degree (J/g * °C)
specific heat of water
4.18 J/g * °C
1 kJ = 1000 J
equation to calculate the amount of heat in joules
Q = mc (ΔT)
Q
Heat gained or lost (Joules or J)
m
Mass in grams of the substance
c
Specific Heat of a Substance
ΔT
Change in Temp. (Final - Initial)
heat of fusion is equal to
amount of heat released when freezing
heat of vaporization is equal to
amount of heat released to condense
heat of fusion formula
Q = m x Hf
heat of vaporization formula
Q = m x Hv
