Unit 2 Energy and Gases Flashcards
What is energy?
The ability of a physical system to perform work
What is the first law of thermodynamics?
Energy can neither be created nor destroyed, only transformed
All types of energy fall under ___
kinetic and potential energy
What is kinetic energy?
the energy of motion
formula for kinetic energy
KE= 1/2 mv2
the higher the temperature, the greater __
KE
What is heat (q)?
the transfer of KE from a substance at a higher temp to a system at a lower temp
What are common forms of energy?
mechanical, heat, bond, light, and electrical
What is the Kelvin scale?
Developed from William Thomson, a temperature scale that begins at 0 and always is a + number
How do you find K from C if the number is measured past the ones place?
C + 273.15
How do you find K from C if the number is whole?
c + 273
What does potential energy depend on?
attraction and repulsion
What is chemical energy?
The potential energy that’s made available during a chemical reaction where bonds are broken and formed
When bonds form, energy is _
released. Freed to Form!
When bonds are broken, energy is _
required. Takes to Break
What is an endothermic reaction?
when heat is absorbed by the process (indicates positive enthalpy). Transferred from surroundings to system
What is an exothermic reaction?
When heat is lost, indicating negative enthalpy. Heat transferred from the system into the surroundings
What is enthalpy?
the amount of heat energy lost or gained by a system during a process at constant process
What happens as a solid is heated?
the particles vibrate faster and faster until they have enough energy to break away from their fixed positions
What happens as a liquid cools?
the particles lose energy and move more and more slowly. When they settle in fixed positions, the liquid has frozen or solidified
The volume of liquids and solids are
fixed
What is the kinetic molecular theory of gases
A theory that helps us understand why gases behave the way they do and gives us insight into the behavior of solids and gases.
Gases are mostly empty space because
they consist of molecules whose separation is much larger than the size of the molecules themselves
What path and direction to particles in gases move?
Straight and random
Describe the collisions of gas particles.
Frequently with sides of the container and less frequent with each other. Elastic, meaning no energy is gained or lost, only transferred
Do particles of a gas attract or repel each other?
No
KE is proportional to (x) in a gas
temp
The kinetic molecular theory of gases applies to
ideal gases
Be sure to study phase diagrams.
Ok
What is critical temperature?
above this temperature, a gas cannot be liquified
What is critical pressure?
The pressure at critical temperature
What is the triple point?
The point at which 3 states exist
What is Boyle’s Law?
P1V1 = P2V2. When pressure increases, the volume decreases and vice versa. Inverse. Make sure to study the graphs in the notes.
Charles’ Law
V1 / T1 = V2 / T2. When temp. increases, the volume increases. Direct.
The temperature must be in Kelvin whenever you…
use the gas laws
What is Gay Lussac’s law?
P1 / T1 = P2 / T2. When the temperature increases, the pressure increases. Direct.
What is Avogadro’s Law?
V1 / n1 = V2 / n2. The volume and amount of gas varies directly. Equal volumes of gases at the same temp and pressure contain equal numbers of particles, even if gases are different.
What is Dalton’s law of partial pressure?
The total pressure of a mixture of gases is simply the sum of the individual pressures of each of the gases (known as partial pressures)
When do you use Dalton’s Law of Partial Pressure?
when you have a mixture of 2 or more gases which do not react chemically
When does Dalton’s law hold true?
when the pressures you are adding together were all recorded at the same temperature and volume conditions
Equation for Dalton’s law
Ptotal = Pa + Pb + Pc…etc
The pressure of a gas collected over water is a combo of…
the pressure of the gas and the pressure of the water vapor
If you see the words “over water” in a problem, you must …
subtract the water vapor pressure from the total pressure of the gas collected over the water
Formula for the Ideal Gas law
PV = nRT
