Final Vocab Flashcards
Boyles law
As pressure increases volume decreases
Charles law
As temperature increases volume increases
Avogadro’s law
As volume decreases moles of gas decreases
Standard temperature and pressure
0°C and 1 atm
Diatomic molecules
Hydrogen, oxygen, nitrogen, chlorine, bromine, iodine, fluorine
Moist air density compared to dry air
water displaces heavier molecules, moist air has smaller average molar mass so it is less dense than dry air
Dalton’s law
Gas will mix with H2O vapor when collected over water: Pgas =Ptotal - Pwater
Assumptions for ideal gas behavior
random motion negligible molecular volume negligible forces constant average kinetic energy average kinetic energy proportional to temperature
Random motion
Gases consist of large number of molecules are in constant random motion
Negligible molecular volume
Gas molecules have negligibly small volume, volume of gas is the volume of the container
Negligible forces
There are no attractive or repulsive forces between molecules
Constant average kinetic energy
Collisions are elastic–> kinetic energy is conserved during collision, they bounce off each other
Average kinetic energy proportional to temperature
Average kinetic energy of molecules is proportional to absolute temperature in Kelvin, at any given temperature of the molecules of all gases have the same average kinetic energy
Temperature
Measure of the average kinetic energy of molecules
High kinetic energy means
High temp
Pressure
Molecular collisions with container walls
More collisions means
Higher temperature
More forceful collisions means
Higher pressure
greater kinetic energy means
Higher average speed, maximum in distribution shifted to higher speed
Same mass at different temperatures
Higher temperature, higher average speed
Different molecules at the same temperature
high mass, low speed
Why do real gases deviate from ideal behavior
They’re attractive forces between gas molecules at high-pressure
Real gas laws have a finite volume, Vanderwall’s equation
Real gas behavior at low pressure
Behave ideally, no attractive or repulsive forces
Real gas behavior in an intermediate pressure
Repulsive forces dominate, volume less than expected for an ideal gas at given pressure and temperature
Real gas behavior high pressure
Repulsive forces dominate, volume greater than expected for an ideal gas at given pressure and temperature
Gases
Interaction between molecules can be neglected
Liquids
Attractive forces between molecules, liquids are more dense than gas
Solids
Strong attractive forces effectively lock molecules in place
Dispersion forces
Attractive interactions between neutral molecules caused by movement of electrons within atoms
Dipole-dipole interactions
Interactions occur between polar molecules with a permanant type of moment
Hydrogen bonding
Attractive force between hydrogen atoms, primarily in 0H NH or FH bonds Hydrogen bonds raise the boiling point of molecules
Ion dipole force
Occur between ions and polar molecules
viscosity
Resistance of fluid to flow, the thickness of the liquid, InLiquids viscosity is due to attractive forces between molecules
Stronger attractive forces means
Higher viscosity
Increases temperature __ viscosity
Decreases
Why does temperature decreases viscosity
The temperature measures the average kinetic energy, molecules have more energy to overcome forces, high kinetic energy makes it easier to overcome attractive forces
Surface tension
Attractive force between molecules on the surface and the bulk liquid, liquids want to minimize surface areas, droplets and bubbles are spherical because a sphere has the minimum surface area for a given volume
Capillary action
When a small diameter tube is placed in a container of water the level of water in the tube is higher than the level in a container
endothermic Phase changes
Solid to liquid: fusion
Liquid to gas: vaporization,
solid to gas: sublimation
Boiling point
At DeltaH of vaporization
Melting point
at Delta H fusion
Critical temperature
The temperature above which liquid cannot exist
Critical pressure
Pressure above which a gas cannot exist
Supercritical fluid
When temperature is a critical temperature and pressure is at critical pressure it has properties between a gas and a liquid, can be used to separate mixtures
Vapor pressure
Pressure of the gas phase in equilibrium with the liquid
Vapor pressure_with temperature
Increases
What happens at boiling point
Temperature where the vapor pressure is equal to the atmosphere pressure
Normal boiling point
Temperature where the vapor pressure is 1 atm
Volatile
Substances with low boiling points
Rate of a chemical reaction
Change in concentration divided by change in time
What happens if you double the concentration at zero order
Rate is unchanged
Half-life
Time required for half of the original amount to react
Activation energy
Minimum energy required for a collision to result in a reaction Ea, represent a potential energy barrier that must be overcome for a reaction to occur
high temp molecules _____, _____ to overcome barrier
High temperature=molecules have more energy = easier to overcome energy barrier
high temp _____ reaction rate
High temperature, high reaction rate
Endothermic
End up with more energy than you started with on the graph, higher, higher activation energy in forward direction
Exothermic
End up with less energy on the graph, lower, higher activation energy in reverse direction
Bigger activation energy means
Slower rate
Intermediate
Something that is formed in one step, consumed in another, and does not appear in the overall reaction
What predicts second order
One step mechanism
What predicts first order
Two step mechanism with a slow first step
Catalyst
speeds up Chemical reaction without being consumed, works by lowering the activation energy for the reaction, has no effect on the equilibrium position for the reaction
lnA vs T
Straight line for first order
1/A vs T
Straight line for second order
A vs T
Straight line for a zero order
Chemical equilibrium
State where concentrations of reactants and products stay constant with time
Large equilibrium constant equals
Mostly products
Small equilibrium constant equals
Mostly reactants
Q>K
Too many products reaction goes in reverse, reverse rxn is spontaneous
Q
To my reactants reaction goes forward, forward rxn is spontaneous
Add product
Shifts in reverse to remove product
Add reactant
Shift forward to remove reactant
Remove product
Shift forward to form product
Remove reactant
Shift reverse to form reactant
Decrease volume increase pressure
System shifts to make less gas in order to decrease pressure
Increase volume decrease pressure
System shifts to make more gas in order to increase pressure
Increase temperature
System shifts in endothermic direction to remove heat
Decrease the temperature
System shift and exothermic direction to add heat
Bronsted acid
Donates H+
Bronsted base
accepts H+
Amphiprotic
Act as an acid or a base
pH=
-log[H+]
[H+]=
10^-pH
pOH=
-log[OH-]
[OH-]=
10^-pOH
14=
pH+pOH
10^-14
[H+][OH-]
Strong acid
ionizes completely to form H+ and a neutral anion
Common strong acids
HCl, HBr, HI, HNO3, HClO4, H2SO4
Neutral anions
Cl-, Br-, I-, NO3-, ClO4-
Strong base
Ionizes completely in water to form OH- and a neutral cation
Common strong bases
LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2, Sr(OH)2, Ba(OH)2
Neutral Cations
Li+, Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+
Weak Acid
Produces only a few ions in a solution
Polyprotic acid
Loses an H but did not lose all of them, has more than one hydrogen dissociate in water
The strongest conjugate base will have
Smallest KA because it’s the weakest acid
Buffer
Consists of nearly equal amounts of a weak acid and its conjugate base, used to maintain constant pH
How can buffers be prepared
add weak Acid to conjugate base,
add strong base to weak acid (conjugate base will form)
add strong acid to weak base (conjugate acid will fomr)
Buffer capacity
Amount of a strong acid or strong base a buffer can absorb without changing
pH
more acid than base in buffer, increase capacity to absorb strong base
pH>pKa
more base than acid in the buffer, increase capacity to absorb strong acid
First law of thermodynamics
Conservation of energy, energy cannot be created or destroyed
Entropy
Measure of disorder or randomness more disorder means higher entropy
deltaS>0
disorder increase
deltaS<0
disorder decreases, order increases
Second law of thermodynamics
For a spontaneous process entropy of the universe must increase
How does temperature affect entropy
Entropy will increase
How does size and complexity effect entropy
Entropy will increase with larger molecules
What sign do entropy and enthalpy have during a phase change
Both have same sign
Third law of thermodynamics
Entropy of pure crystalline solid is zero at absolute zero
deltaG<0
forward reaction is spontaneous
deltaG>0
reverse reaction spontaenous
Delta H negative
Delta S positive
Always spontaneous
Delta H positive
Delta S negative
Never spontaneous
Delta H positive
Delta S positive
Spontaneous at high temperatures
Delta H negative
Delta S negative
Spontaneous at low temperatures
A large negative delta G
K>1, products favored
Large positive Delta G
K<1, reactants favored
for a spontaneous process the size of delta G represents
The amount of energy available to do useful work
Free non-spontaneous process the size of delta G represent
The amount of work needed to make the reaction go
Oxidation
Loss of electrons oxidation number increases
Reduction
Gain of electrons oxidation # decreases
What does an oxidizing agent cause
Oxidation, it contains the species reduced
What does a reducing agent cause
Reduction, it contains the species oxidized
Voltaic cell
Uses spontaneous redox reaction to generate electrical energy from chemical energy
Electrode
Strip of metal
Electrochemical cell
Consist of two electrodes immersed in solution and connected by a salt bridge
Salt bridge
Maintains electrical neutrality by allowing ion movement
Where does reduction occur
Cathode
Where does oxidation occur
Anode
The first element in line notation
Anode
The last element in line notation
Cathode
The stronger the oxidizing agent
The more positive the reduction potential
The stronger the reducing agent
The more negative the reduction potential
An oxidizing agent will oxidize anything
Below it, on the left
A reducing agent will reduce anything
Above it, on the right
Electrolysis
Electrolytic cells are used to convert electrical energy into chemical reactions
Electrorefining
Extract metal from ores
Metal plating
Make the object to be plated at the cathode and place it in a solution containing ions of the metal to be plated. A thin film of metal will code the surface
a wet cell
Lead storage battery, the electrodes are immersed in a solution, is rechargeable from the cars alternator, both anode and cathode are immersed in H2SO4 solution
Dry cell
Contains a moist paste between electrodes, ex common battery, anode:Zn, coathode:graphite
Alkaline batteries
Use koh instead of NH4CL making them basic, last longer, can handle higher currents
Silver cell
Overall reaction contains no ions so voltage stays constant at E0 throughout lifetime battery, cathode: Ag2O, Anode: Zn
Lithium ion battery
High voltage, high energy per unit volume, rechargeable
Corrosion
Oxidation of metals, the magnitude of the Ered for a metal indicates the ease of oxidation which often correlates with susceptibility to corrosion
Galvanizing
Process where a coating of zinc oxide is placed on surface of intron to protect the metal underneath from Rusting
Inexpensive batteries
contain ZnCl2 and NH4Cl in paste making them acidic
what is special about aluminum
so easily oxidized that a thin coating of Al oxide forms on the surface, which protects the metal underneath
