Ch. 7 Flashcards
physical change is caused by what? what TD quantity is closely related to change
changes inintermolecular forces between molecules or atoms NOT INTRAMOLECULAR (molecules interacting with other molecules causes changes). Temp is related to change
entropy does what as we go from solid to gas
solid: lowest KE and lowest entropy
liquid: medium
gas: highest KE and highest entropy
solid to liquid is called
fusion or melting
liquid to solid is called
crystallization or freezing
liquid to gas is called
vaporization or boiling
gas to liquid is called
condensation
solid to gas is called
sublimation
gas to solid is called
deposition
as KE and S increases, heat is what?
as KE and S decreases, heat is what?
as it increases: absorbed
as it decreases: released
what is heat of transtion
the amount of energy required to complete a transition “heat of fusion or heat of condensation, etc)
amount of heat is dependent on
- type of substance and 2. amount of substance
what is calorie
amount of heat required to raise temp of 1 gram of water by 1 Celsius. 1 Cal=4.2 Joules
when a substance absorbs or releases heat what will occur
it will change temp or undergo a phase change, both will not occur at same time.
what is heat capacity
amount of HEAT to be supplied to an object to produce a unit change in its temperature, temp is inversely proportional to heat capacity
what is specific heat
how resistant it is to change in temp, the amount of ENERGY needed to change temp
what is a phase transition diagram?
a graph that states that as heat is added to a substance, its temp will rise until it reaches a transition state. once it hits a transition state, the energy inputting is towards changing transition until it finishes and raises temp to reach next transition state
what two main things causes a phase change
temp and pressure
what are boundary lines in the phase transition diagram?
when phases are in equilibrium
at 1 atm, temp at this point is called
normal melting or boiling point at certain boundary lines
what is the triple point
temp and pressure in which all 3 phases exist simultaneously at equilibrium
what is critical point? what is the phase that occurs after this point?
a critical point marks end of liquid-gas boundary and it creates supercritical fluid that no matter how high pressure, it cant become a liquid. it has high density and low viscosity
what makes water special in its phase changes
it is denser in liquid phase than its solid phase making the solid liquid boundary to have a (-) slope compared to (+) like most other molecules
how can you tell if a compound has strong IMF
Ionic and polar covalent compounds because they are more EN and can interact with more molecules if they can h-bond
if a compound that is both liquid and solid is at equilibrium, what combination of liquid and solid should have lowest temp?
all combinations have temp at 0 because its at equilibrium
when H and q is positive , what is heat
absorbed
when H and q is negative, what is heat
released
1 calorie is what in joules
4.2
which solid will exhibit the smallest change in temp? Al (0.9), Pb (0.1), or Sn (0.2) (numbers are specific heat)
Al because it has highest specific heat and temp and specific heat are inversely proportional.
what is formula to find amount of heat needed for a phase change?
q=n x H where n is number of moles and H is heat of transition
temp is proportional to
q heat added/released by a sample
Measurement of Heat Changes (calorimetry) formula
q=mc(delta)T where m is mass, c is specific heat, and t is temp change
from right to left, where are the phases on the phase diagram
solid (left top side), liquid (middle), and gas (right and bottom)
waters melting/boiling point increases as pressure
decreases
A chemical that has weak intermolecular forces will be volatile or non-volatile
Volatile. Chemicals that act as hydrogen donors and receptors have increased intermolecular forces, causing them to be less volatile.
