Unit 7 Review Flashcards
states of matter & properties of fluids
Provide the term: An explanation of how the particles in gases behave.
kinetic theory
The kinetic theory is also known as the kinetic molecular theory.
What are the four assumptions of the kinetic theory?
PRCE
- All matter is composed of tiny particles1
- These particles are in constant, random motion
- The particles collide with each other and with the walls of any container in which they are held.
- The amount of energy that the particles lose from these collisions is negligible.
PARTICLES, RANDOM, COLLIDE, ENERGY
1 Atoms, molecules, and ions
What is a solid?
the state of matter that has a definite shape and volume
the particles in this state do not move fast enough to overcome the attraction between eachother
solid
the particles in this state move quickly and can break away completely from one another
gas
True or false: In a solid, each particle vibrates in place and is locked in place by the particles around it.
True
What are the two types of solids?
- Crystalline
- Amorphous
What type of solid is this?
Crystalline
Crystalline solids have a very orderly, three-dimensional arrangement of particles.
What are some examples of crystalline solids?
- iron
- diamond
- ice
What type of solid is this?
amorphous
Amorphous solids are made of particles that do not have a special arrangement.
What are some examples of amorphous solids?
- glass
- rubber
- wax
What is gas?
the state of matter that has no definite shape or volume
True or false: The amount of empty space between gas particles cannot change.
False
What is liquid?
the state of matter that has a definite volume but takes the shape of its container
the particles of this state move fast enough to overcome some of the attraction between them
liquid
the particles in this state slide past each other
liquid
When you put ice in your drink, why does it eventually melt?
the particles that make up the water are moving fast and colliding with the particles that make up the ice cube
This transfers energy from the water to the ice. The particles at the surface of the ice cube vibrate faster, transferring energy to other particles in the ice cube. Eventually, the ice particles move fast enough to become liquid.
A change of state is the change of a substance from one _______ form to another.
physical
Arrange the three states of matter based on how fast they move.
(1 being the slowest, 3 being the fastest)
- Solids - vibrate
- Liquids - flow
- Gases - bounce
What is melting?
the change of state from a solid to a liquid
What is the melting point1 for water?
anything above 0˚ Celsius
1 The temperature at which a solid changes to a liquid.
Provide the term: The energy required to change a substance from a solid to a liquid.
Heat of fusion (Hfus)
The heat of fusion is the amount of energy required to change a substance from a solid to a liquid at its melting point. It represents the energy needed to overcome intermolecular forces without changing the temperature. In short, the melting point is a temperature, while the heat of fusion is an amount of energy required for the phase change.
For a solid to melt, particles must overcome their __________ to each other.
attraction
What is the difference between an endothermic change and an exothermic one?
- Endothermic - adding (absorbing) energy
- Exothermic - removing (releasing) energy
What is a freezing point?
The temperature at which a liquid changes to a solid
The freezing point for water is 0˚ Celsius
Does melting only occur at the melting point?
Yes
Melting occurs only when a substance reaches its melting point. For example, ice melts at 0˚C, and at this temperature, added heat goes into breaking molecular bonds rather than raising the temperature.
What is the heat energy equation?
Q = mHfus
Q = heat energy (in joules)
m = mass of the substance (in grams)
Hfus = heat of fusion which is the amount of energy required to melt 1 gram of the substance
Provide the term: the change of state from a liquid to a gas
evaporation
What is boiling?
the change of a liquid to a gas throughout the liquid
True or false: Evaporation can occur at the surface of a liquid that is below its boiling point.
True
At the liquid’s surface, some particles have enough kinetic energy to escape attractive forces of the liquid.
What is the difference between evaporation, boiling, and vaporization?
- Evaporation - Occurs only at the surface of a liquid
- Boiling - Occurs throughout the entire liquid
- Vaporization - The overall term for both processes
True or false: If water is at 89˚ Celsius, then it is boiling.
False
Boiling only occurs at temperatures at or above the boiling point.
Provide the term: the amount of energy required to change a liquid to a gas
Heat of vaporization (Hvap)
The formula for vaporization is Q = mHvap
As atmospheric pressure decreases, the ___________ of a liquid decreases too.
boiling point
True or false: The boiling point of water is lower at sea level than it is at the top of mountains.
False
Atmospheric pressure is lower at higher elevations, meaning so is the boiling point of liquids.
What is condensation?
the change of state from a gas to a liquid
True or false: Condensation is the reverse of vaporization.
True
What is the condensation point of water?
100˚Celsius
The condensation point of a substance is the temperature at which the gas becomes a liquid. It’s the same as the boiling point, but in reverse.
What is the energy formula for condensation?
Q = mHvap
Hvap is negative because condensation releases energy.
What is sublimation?
the change of state in which a solid changes directly into a gas
Sublimation happens when molecules in a solid gain enough energy to break free from their attractions and become gas.
What is deposition?
the change of state in which a gas changes directly into a solid
Deposition is an exothermic change.
When most substances lose or gain energy, one of two things happens to the substance. What are they?
- its temperature changes
- its state changes
The temperature of a substance does not change until a change of state is complete.
Provide the term: Matter that has enough energy to overcome not just the attractive forces between its particles but also the attractive forces within its atoms.
plasma
What is the most abundant form of matter in the universe?
plasma
True or false: When objects get warmer, they contract.
False
Particles move faster and farther apart as the temperature rises. This separation of particles results in an expansion of the entire object, known as thermal expansion.
What is Archimedes principle?
states that a buoyant force on an object is equal to the weight of the fluid displaced by the object
What is buoyancy?
the ability of a fluid–a liquid or a gas–to exert an upward force on an object immersed in it
How do ships stay afloat?
because their shape makes their density less than the water
A small steel ball sinks because it’s dense and doesn’t displace much water. A steel bowl floats because its spread out, displacing more water and creating a stronger buoyant force.
True or false: If an object floats, it’s less dense than the substance that it’s floating in.
True
What is the density of water?
1
Ice has a density less than 1
The idea that applied pressure is transferred equally throughout a contained fluid is also known as…
Pascal’s Principle
How can Pascal’s Principle be written out?
(as an equation)
pressure in = pressure out
Provide the equation for pressure.
force exerted per unit area
P = F / A
How do car brakes work?
Car breaks use a hydraulic braking system, which multiplies the force from your foot to stop the car
When you press the brake pedal, it pushes a piston which is filled with brake fluid. The brake fluid moves through the brake lines to each wheel, transferring force. Because liquids can’t be compressed, this allows a small force from your foot to be multiplied. The force is transmitted to the large pistons that push on the brake pads.
Daniel Bernoulli was a ______ scientist who studied the properties of moving ______, such as water and air.
Swiss, fluids
What does Bernoulli’s principle state?
as the speed of a moving fluid increases, the fluid’s pressure decreases
Airplane wings are shaped with a curved top and a flatter bottom. When air moves over and under the wing, the curved top causes air to move faster, lowering the pressure. The flattter bottom causes air to move slower, creating higher pressure. In the end, lift is created, as higher pressure below pushes up while the lower pressure above pulls up.
What is viscosity?
the resistance of a fluid to flowing
Cold syrup flows slowly because it has high viscosity, while heated syrup flows easily because it has low viscosity.
What are the units for pressure?
Pa
True or false: Fluids (naturally) from low to high pressure.
False
How does shape affect floating or sinking?
it influences how much water an object displaces, which directly impacts the buoyant force acting on it
The buoyant force is equal to the weight of the fluid displaced. So, if an object pushes more water out of the way, it experiences a stronger upward force, making it more likely to float.
What does Boyle’s law state?
(advanced)
If you decrease the volume of a container of gas and hold the temperature constant, the pressure from the gas will increase
And vice versa
Why should you always exhale when rising from deep in the ocean?
(advanced)
As you ascend, the pressure around you decreases, causing the air in your lungs to expand
If you hold your breath, the expanding air can overinflate and rupture your lungs, leading to serious injury or even DEATH!
Provide Boyle’s Law Equation.
(advanced)
initial pressure x initial volume =
final pressure x final volume
PiVi = PfVf
What does Charles’s law state?
(advanced)
the volume of a gas increases with increasing temperature, as long as the pressure on the gas does not change
Provide an example of Charles’ law in action.
(advanced)
when hot-air balloons heat their air so they can rise higher
In a hot air balloon, the burner heats the air inside the balloon, causing the air molecules to move faster and spread out, increasing the volume while decreasing its density. Since hot air is less dense than the cooler air outside the balloon, buyoant force lifts the balloon into the sky.
Provide Charles’ Law Equation.
(advanced)
initial volume / initial temperature =
final volume / final temperature
Import into Notability and complete; you should have already
Bernoulli’s principle will be one of the short answers on the test. Provide examples to show your understanding.
- Airplane Wings (Lift Generation) - Air moves faster over the curved top of the wing than underneath, creating lower pressure on top and higher pressure below, which lifts the plane.
- Shower Curtain Effect - When water flows from a showerhead, it speeds up the air, lowering pressure and pulling the curtain inward.
- Roof Lifting in Storms - Fast-moving wind over a roof lowers pressure, sometimes lifting it off if the pressure inside is higher.
- Vaccum Cleaner - A vaccum cleaner creates a low-pressure area through the fan, which then draws in air and dirt from the higher-pressure outside environment, creating suction.
These all demonstrate how fluid speed affects pressure.
A weather balloon has a volume of 100 L when it is released from sea level, where the pressure is 101 kPa. What will be the balloon’s volume when it reaches an altitude where the pressure is 43 kPa?
use Boyle’s Law Equation
235 L
final volume: Vf
initial pressure = 101 kPa
initial volume = 100 L
final pressure = 43 kPa
set up the problem: PiVi = PfVf
