lecture 1 tdp2

define first law of thermodynamics

the total energy of an isolated system is constant; energy can be transformed from one form to another but can be neither created no destroyed

what is the key principle of the first law of thermodynamics

what is the key concept of the first law of thermodynamics

what is the symbol and units of the first law of thermodynamics

conservation of energy

energy

E and Joule / J

what is the conservation of energy

in a closed system, energy cannot be created or destroyed. it can only be transformed from one form to another. the energy of our universe is constant

what is a thermodynamic system is

a system [eg. beaker, earth], surroundings [eg. universe] and a system boundary

what does the first law of thermodynamics relate to

the internal energy of a system to the amount of heat added to the system and the amount of work done on the system

when is work done

when a force is applied to an object and that causes the object to move a distance

define the zeroth law

"if 2 systems are each in thermal equilibrium with a third, they are in thermal equilibrium with each other"

allows us to do experiments

key concept = temperature

symbol = T

units = K, kelvin

why is thermodynamics important

we can interconvert:

• kinetic energy, chemical energy, heat, work, light, nuclear energy

applies to:

• atoms and molecules, chemical bonds, photons and electrons, biology, engineering, earth science, the universe

how to draw an energy reaction coordinate diagram

see page 8 of booklet

why are chemistry, bonds and the first law important

to consider the bonds broken and formed

define an open system

can exchange heat and matter

eg = beaker, human body and cells

define a closed system

exchange only heat

eg = light bulb, solar panel

define isolated system

no exchange of heat or matter

eg = perfect thermos, bomb calorimeter

define isothermal change

has a diathermal wall [exchange heat not matter]

temperature of the system stays the same as the surroundings

is a closed system

define adiabatic change

no heat transfer

isolated system, no exchange of heat between system and surroundings

perfectly isolated system

has an adiabatic wall

transfers energy only as work

in a breitling orbiter, what type of system is the helium balloon

closed system

otherwise helium would be displaced for air

in a breitling orbiter, what type of system is the hot air balloon

open system

needs to be able to expand and lose mass

in a breitling orbiter, what type of system is the propane burner

open system

needs to exchange heat and matter

is planet earth an open, closed, or isolated system

assume closed system is not isolated → exchange heat and light

some loss of helium / hydrogen but close to negligible