Chapter 3: Matter and Energy Flashcards
What is a molecule?
2 or more atoms is a molecule
Classify the following matters in terms of states, volume, shape; etc…
Solid, Liquid, Gas
Solid = Rigid shape, fixed volume Gas = Spread out, compressible, assume shape of container Liquid = Close to one another, flexible, assume shape of container
What’s the difference between crystalline and amorphous solids?
Crystalline shapes - atoms or molecules are in Geometric Patterns (neater)
Amorphous shapes - do not have long-range order (not order)
T or F: Compounds are NOT pure substances because they contain more than 1 element.
False - compounds ARE pure substances because they can be easily decomposed into simpler substances.
Water, table salt, sugar are all examples of what?
elements
molecules
compounds
mixture
water, table salt, and sugar are all COMPOUNDS - they contain more than 1 element that reacted to one another.
If we are heating sugar over a flame, what are we doing to the compound?
We start to decompose sugar into simpler substances such as carbon (element) and gaseous water (different compound).
Is air a compound or mixture? Explain.
Air is actually a MIXTURE - it is composed of nitrogen and oxygen gas.
Is salt water a homogenous or heterogenous mixture? Explain.
Salt water is a homogenous mixture - the composition is the same throughout.
Classify the following matter as pure substance or mixture… classify specifically:
a. lead weight
b. seawater
c. distilled water
d. salad dressing
a. lead weight: pure substance - element
b. seawater: homogenous mixture
c. distilled water: pure substance - compound
d. salad dressing: hetero mixture
What is one question I should ask myself when determining if something is a physical or chemical property?
What are some good tips?
“Is there a CHANGE in COMPOSITION?”
+Even though water boils and turns into gas, it is STILL THE SAME OLE WATER - it did NOT change Chemically.
Determine whether the following is a physical or chemical property:
a. boiling point of water
b. copper turns green when exposed to air
c. automobile paint dulls over time
d. gas evaporates quickly when spilled
e. low mass (for a given volume) of aluminum relative to other metals
f. evaporation of acetone from the skin
g. burning of coal
h. fading of carpet due to exposure to sunlight
a. water boiling = physical
b. copper turns green when exposed to air = chemical; the copper reacts with the gases in the air to form compounds
c. automobile paint dulls over time = chemical; the fading of paint is caused by Decomposition due to sunlight or oxygen.
d. gas evaporates quickly when spilled = physical; it has a low boiling point
e. low mass… of Al relative to other metals = physical; this is due to it’s low density
f. evaporation from acetone = physical; changes from liquid to gas, but STILL the same properties
g. burning of coal = chemical; coal reacts with oxygen to form CO2
h. fading of carpet = chemical; carpet molecules have decomposed due to the exposure to sunlight
In a chemical reaction, what are the substances that are present before the chemical change?
What are the substances called after the chemical change?
Reactants (before)
Products (after)
If a drop of water was placed into a clear bottle, sealed with a cap, then heated until it vaporized - is the mass of the container and water different?
No - according to the law of conservation of mass, matter is neither created or destroyed -thus matter will stay exactly the same mass regardless of a physical or chemical property or change.
The total energy of a sample of matter is the sum of its ___________ energy, the energy associated with its motion, and its ___________ energy, the energy associated with its position or composition.
The total energy of a sample of matter is the sum of its kinetic energy, the energy associated with its motion, and its potential energy, the energy associated with its position or composition.
Water being held behind a dam is considered what type of energy? Explain.
Water behind a dam carries POTENTIAL energy because of it’s high position. Gravity makes it easy for the water to not have to use any energy at all.
