Thermodynamics: Introduction Flashcards
First Law of thermodynamics
The internal energy of an isolated system remains constant
What is thermodynamics?
The branch of physical chemistry concerned with the study of the transformations of energy.
Force is directly proportional to….
Directly proportional to acceleration
Which standard unit depicts force?
Newtons depict this!
What is force the product of?
Mass and acceleration
What is the equation for force?
F = ma
N = kg ms^-2
What is pressure, exactly?
This measure is the force per unit area, (F/A)
What is the equation for pressure?
F/A = N/m^2 = N m^-2 = Pa
What is the definition of energy?
The ability to do work
What is energy the product of, conceptually?
The product of force and distance.
What is the equation for kinetic energy?
Ek = (1/2)mv^2 = (p^2)/2m
What is the definition of potential energy?
The energy stored due to the attractive forces between atomic nuclei and their electrons, or chemical bonds, in molecular interaction.
What are the 4 variables of state? What do they describe?
These variables describe the physical state of any pure substance. They are: V, p, T, and n.
When there is work, what has happened?
When a force, F, moves a body through a distance, D.
What can generally be said about work?
This is done to achieve motion against an opposing force and corresponds to a form of energy transfer.
How does motion differ between the two work equations?
In one equation, motion is against a constant opposing force (gravity). In the other equation, motion is against a changing opposing force (sloping of a hill).
How can a conversion be made from Celsius (oC) to Kelvin (K)?
Celsius + 273.15 !
In which way does temperature determine the direction energy will flow as heat when objects are in contact?
Energy flows from higher temperature to lower temperature.
What is thermal equilibrium?
When the net flow of energy is zero because two bodies have the same temperature.
What is the Zeroth Law of Thermodynamics?
If A is in thermal equilibrium with B, and B is in thermal equilibrium with C, then A and C must also be in thermal equilibrium.
What is Avogadro’s number, with units?
6.022 x 10^23 mol^-1
How can you tell if a property of a substance is intensive or extensive?
An intensive property of a substance retains the same value regardless of the amount of that substance (ie. pressure, temperature, molar volume, molarity)
An extensive property is a value which depends upon the amount of a substance present (ie mass and volume)
What are the variables of state?
Four interdependent quantities which describe the physical state of a pure substance.
V = volume (dm^3)
p = pressure (kPa)
T = temperature (K)
n = # of moles
What is a unique conclusion which can be drawn from the dependent nature of the variables of state?
Knowing the values of three of the variables of state allows the fourth variable’s value to be known without measurement, since they are all interdependent
What is Boyle’s Law?
At a constant temperature, volume and pressure are inversely proportional. That is, an increase in pressure necessitates a decrease in volume, and vice versa.
What is Charles’s Law?
At a constant pressure, the volume of a gas is directly proportional to the absolute temperature.
What is Avogadro’s Principle?
Equal volumes of gases at constant temperature and pressure contain equal numbers of molecules.
What does the Ideal Gas Equation tell us?
It links all of the properties needed to define the state of a gas; it describes the nature of an ideal gas given the four variables of state and the ideal gas constant, R.
What is the Ideal Gas Equation and what are its components?
pv = nRT, where
p = pressure
v = volume
n = # of moles
R = ideal gas constant (8.314 J K^-1 mol^-1)
What is Standard Ambient Temperature and Pressure (SATP)?
A standardized temperature and pressure was defined for use in the ideal gas equation; T = 298.15K and p = 1 bar
What does Dalton’s Law state?
The pressure of a gas mixture is equal to the sum of the individual partial pressures
How do partial moles relate to partial pressures?
The molar fraction of a given gas is equal to the partial pressure of the same substance in a mixture.
How can Boyle’s Law be demonstrated in an equation?
p = constant x 1/V (where the constant is a proportionality constant)
What is unique about the volume of gases at varying pressures at -273.15K?
At varying pressures, the volume of all gases is equal at the temperature -273.15K.
What is the ideal gas constant?
8.314 J K^-1 mol^-1
How does 1 bar convert to Pascals?
1 bar = 10^5 Pa
What is molar volume?
The volume that one mole of a substance occupies, expressed as Vm, in units of m^3mol^-1.
