AP Chem Final Flashcards
What is STP?
Pressure = 1 atm
Temperature = 273 Kelvin
What is important when using ideal gas law?
Pressure is in atmospheres
Temperature is in Kelvin
Volume is in Liters
How do you convert Celsius to Kelvin?
Temperature in Kelvin is Equal to Temperature in Celsius plus 273.15
How do you convert atmospheres to torr and mmHg?
1 atm = 760 torr = 760 mmHg
1 torr = 1 mmHg
What are the conversions you need to know?
2.54 cm = 1 inch
1 kg = 2.2 lbs
What is the 1 mol equal to?
6.022*10^23
What is the ideal gas constant for Kelvin and Atmospheres?
0.0821
What are the names of the equations and the variables of ideal gas law they involve?
Boyle’s Law: P, V
Charle’s Law: V, T
Gay-Lussac’s Law: T, P
Combined Gas Law: P, V, T
Avogadro’s Law: V, n
Ideal Gas Law: P, V, n, T
What is the law you utilize when there is more than one gas in a chamber?
Dalton’s Law
Total Pressure = Pressure of Gas 1 + Pressure of Gas 2 + etc
How do you find the mole fraction of a specific gas in a mixture?
Moles of the Gas/Total Moles
How do you find the pressure of a specific gas given total pressure?
Mole Fraction of the Gas * Total Pressure
What are the three postulates of KMT?
The combined volume of all molecules is negligible relative to the total volume of the gas
The average kinetic energy of molecules in a gas is proportional to the absolute temperature
All collisions are completely elastic (energy can be transferred but not lost, gas will not slow down on its own)
How does heat effect particle speed
The hotter the gas the faster the molecules within it.
What is pressure according to KMT?
Molecules in gas hitting the sides of a container
How does molar mass effect speed?
The higher the molar mass the slower the particles are
What is true of gasses at the same temperature?
They have the same kinetic energy
When does KMT/ideal gas law break down and why does this happen?
Extremely low temperatures or Extremely high pressures
Cause particles DO have volume and DO exhibit intermolecular forces
What factors affect solubility?
Temperature:
Increases solubility of solids
Decreases solubility of gasses
Pressure:
Increases solubility of gasses
What is henry’s law?
C = kP where P is the partial pressure of the gas, k is the henry’s law constant, and C is the concentration of the dissolved gas in equilibrium (in molarity aka mol/liter)
What are the types of energy?
Work: Change in Energy
Kinetic Energy: Energy from motion
Potential Energy: Due to position of composition
Thermal Energy: Associated with temperature
Chemical Energy: Associated with positions of electrons and nuclei
What is an important law for when working with energy?
Conservation of Energy
What is the system and the surroundings?
The system is the objects currently at play
The surroundings are thing outside the system which energy from inside the system gets transferred to
How do you convert from calories to Joules?
1 cal = 4.184 Joules
What are path and state variables?
State variables are the same no matter the path taken
Path variables depend on the path taken
How do you convert from L*atm to J?
1 L*atm = 101.3 J
What is the equation for work related to pressure and volume?
w = -P*ChangeV
Where P is the pressure and V is the change in volume
What are q and w for a system?
Q is the thermal energy
Positive means the system gained thermal energy, negative means the system released thermal energy aka the surroundings gained thermal energy
W is the work
Positive means work was done on the system and negative means work was done by the system
What is change in E for systems problems?
The change in the energy of the system.
Positive means energy flows into the system
Negative means energy flows out of the system
What are the equations that relate energy and temperature?
q = CchangeT
Where C is the heat capacity and changeT is the change in temperature
q = mcchangeT
Where m is mass in grams, c is the specific heat capacity and changeT is the change in temperature
q = MC*changeT
Where M is the number of moles, C is the molar heat capacity, and changeT is the cchange in temperature
How do you solve a problem involving two systems heat capacity equations?
q1 = -q2
m1C1changeT1 = -m2C2changeT2
Tf is the same for both so
m1C1(Tf - T1i) = -m2C2(Tf-T2i)
m1C1Tf + m2C2Tf = m2C2T2i + m1C1T1i
What are general trends in specific heat capacity?
As you go the left specific heat increases and as you go up specific heat increases
What is the energy of a reaction calculated as?
changeE = q + w
How do you measure the energy of a reaction in a bomb calorimeter?
Since volume is constant q is the only relevant factor
Thus
ChangeE = C_calorimeter*changeT = q
q_calorimeter = -q_rxn
What is the enthalpy?
Enthalpy = changeH = q = mCT
So enthalpy is just the heat lost or gained by the system
Notably this is different than changeE the change in energy cause it ignores the change in volume
What are exothermic vs endothermic reactions?
Exothermic reactions release energy (thus has negative enthalpy) while endothermic reactions absorb energy (thus has positive enthalpy)
What is H_rxn?
H_rxn is the enthalpy for a balanced chemical equation
So if the equation is
C3H8(g)+5 O2(g)→3 CO2(g)+4 H2O(g) and ΔHrxn=−2044 kJ
That implies for every 1 mol of C3H8 and 5 mols of O2 that is reacted to for 3 mols of CO2 and 4 mols of H20 2044kJ are released from the system.
How do you utilize a coffee cup calorimeter to find Hrxn?
-q_soln = -mCchangeT = q_rxn = q_p
H_rxn = q_p/mols of reactant
MAKE SURE TO UTILIZE NEGATIVE
What happens if you reverse a chemical reaction? what if you have enough reactants to do it twice?
It reverses the H_rxn aka it multiplies the value by -1
the H_rxn is doubled
How do you calculate H_rxn using standard heats of formation?
H_rxn = H_products - H_reactants
How do you find change E for a coffee cup calorimeter?
First find the calorimeter constant using water (if the problem requires). Enthalpy is equal to q_soln + q_calorimeter if it does and just q_soln if it doesn’t
Then changeE = Enthalpy + PchangeV
What is the speed of light in m/s?
3*10^8 m/s
What is amplitude wavelength and frequency?
Amplitude is the height of peaks of a light wave, wavelength in the distance between two peaks, frequency is the number of cycles which occur per second.
What is the relationship between frequency and wavelength?
Frequency = Speed of Light / Wavelength
What are interference and diffraction?
Interference is the process by which waves either amplify or destroy each other.
Diffraction is the process where waves going through a slit similar in size to their wavelength bend around it.
What is the energy of a photon?
E = hv
What is Planck’s constant?
6.626*10^-34 J s
Who found the photo-electric affect?
Albert Einstein
Who found black-body radiation?
Max Planck