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115 Cards in this Set
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Define Pressure |
the force exerted per unit area by gas molecules as they strike the surface around them |
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Expanded volume results in a lower concentration of what? What happens to the pressure? |
Gas molecules but the number of gas molecules does not change; lowers the pressure |
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Formula for pressure |
P = F/A |
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What happens to the pressure when altitude increases? |
Pressure decreases |
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Name common units of pressure |
mmHg - often called a torr
atm
pascal (Pa)
in Hg
psi |
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Define atmosphere |
the average pressure at sea level |
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Define barometer |
an evacuated glass tube, tip is submerged in a pool of Hg |
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1 atm = ________ torr |
760 torr |
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1 Pa = __________ N/m squared |
1 N/m squared |
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What is the SI unit for pressure? |
Pascal |
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1 atm = ____________ Pa |
101,325 Pa |
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1 atm = ___________ in Hg |
29.92 in Hg |
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1 atm = __________ psi |
14.7 psi |
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What is a way to measure pressure in a lab? |
The manometer |
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Define a manometer |
a U-shaped tube containing a dense liquid, usually Hg - always measures pressure of the gas sample relative to atmospheric pressure |
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What are the Simple Gas Laws? |
Boyle's Law Charles Law Avogadro's Law |
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Boyle's Law is related to? |
Volume and Pressure |
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What is the relationship between Volume and Pressure? What law is it related to? |
Inverse relationship; Boyle's Law |
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What is the formula between Pressure and volume?? |
P1V1 = P2V2 |
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Charles Law involves what? |
Volume and Temperature |
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What is the relationship Volume and Temperature? What law is it related to? |
As volume goes up, temperature goes up
The two are linearly related |
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What is considered absolute zero? |
-273.15 degrees C |
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What is the formula between Volume and temp? What law is it related to? |
V1 / T1 = V2 / T2
Charles Law |
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What does Avogadro's Law Involve? |
Volume and Amount (in moles) |
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What is the relationship between volume and amount (in moles)? |
As volume goes up, amount in moles goes up because they are directly proportional |
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What is the formula between Volume and amount in moles?
What law is it related to? |
V1 / n1 = V2 / n2
Avogadro's Law |
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What is the Ideal Gas Law? |
PV = nRT
R = ideal gas constant = 0.08206 L * atm / mol * k |
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As temp of a fixed amount of gas in a fixed volume increases, pressure ____________.
What is this called? |
increases
gay-lussac's law |
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What is gauge P? |
the difference between total P and atmospheric P |
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Define Molar V |
the volume occupied by one mole of a substance |
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Standard temp: |
0 degress C or 273 k |
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Standard P: |
1 atm |
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Molar V at STP: |
22.4 L |
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What is the formula for density? |
Molar mass / Molar Volume
moles / liters |
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d = ? |
PM / RT |
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What is the composition of air? |
- Nitrogen 78% - Oxygen 21% - Argon 0.9% - CO2 0.04% |
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Define Partial Pressure |
the P due to any individual component in a gas mixture (Pn) |
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Formula for partial pressure |
(Pn) = n * RT/V |
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What is Dalton's Law of partial pressures? |
Sum of partial pressures: P total = P(a) + P(b) + P(c) + ........ |
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Mole fraction: |
x(a) = n(a) / n(total)
or
P(a) = x(a) * P(total) |
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Define hypoxia |
low oxygen levels produce the psychological condition ~ oxygen starvation |
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Define oxygen toxicity |
increased oxygen concentration in the body tissues |
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Define Nitrogen narcosis |
increased P(N2) beyond 4 atm in the body tissues ~ rapture of the deep
-often happens to divers |
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Define Vapor P |
the partial P of water in the mixture - increases with increasing temp |
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What is the partial pressure of H2O? |
23.78 mmHg (its vapor P at 25 degrees C) |
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What is the Kinetic Molecule Theory |
the simplest model for the behavior of gases |
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What are the 3 basic assumptions of the kinetic molecular theory? |
1) The size of a particle is negligibly small 2) The avg kinetic energy of a particle is proportional to the temp in kelvins 3) The collision of one particle with another (or with the walls of its container) is completely elastic |
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What is the formula for Kinetic Energy? |
KE = 1/2 m v^2 |
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What is the formula for KE (avg)? |
KE(avg) = (3/2)RT |
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What is the formula for the root mean square velocity? |
U(rms) = square root of 3RT/M
M must be in kg/mol |
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Define the Mean Free Path |
the average distance that a molecule travels between collisions - increasing with decreasing temp |
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Define diffusion |
the process by which gas molecules spread out in response to a concentration gradient - can be influenced by the root mean square velocity |
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Define Effusion |
the process by which the gas escapes from a container into a vacuum through a small hole |
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What is the formula for Grahams law of effusion? |
rate a ______ = square root of M b / M a rate b ^molar masses |
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What is Waal's corrected ideal gas equation? |
V = nRT + n*b
n = # of moles b = constant that depends on the gas |
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Define Intermolecular Forces |
attractions between the atoms or molecules that compose any substance |
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What is the corrected ideal behavior equation for intermolecular forces (by Waal's again)? |
P = nRT / V - a (n/v)^2
n = # of moles V = Volume a = constant that depends on the gas |
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What is the total Van der Waals Equation? |
[P + a (n/v)^2]*[V - n*b] = nRT |
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What is the equation for Real Gases? |
PV/RT |
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Define Thermochemistry |
the study of the relationships between chem and energy |
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Definition of exothermic |
releasing heat |
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Definition of endothermic |
absorbing heat |
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Define energy |
capacity to do work |
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Define work |
the result of a force acting through a distance |
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Define heat |
the flow of energy caused by a temp difference |
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Define Kinetic Energy |
the energy associated with the motion of an object |
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Define thermal energy |
the energy associated with the temp of an object - type of KE because it arises from the motions of atoms or molecules within a substance |
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Define PE |
the energy associated with the position or composition of an object |
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Define chemical energy |
the energy associated with the relative positions of electrons and nuclei in atoms and molecules - form of PE |
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What does the law of conservation of energy state? |
That energy can neither be created nor destroyed |
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In an energy exchange, where is energy transferred? |
Between the system and the surroundings |
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What are the units of energy? |
Joules
cal
Cal |
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What does 1 Joule break down to? |
1 J = kg * m^2/s^2 |
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1 Cal = _______ cal |
1 Cal = 1 kcal = 1000 cal |
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1 cal = ________ J |
4.184 J |
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1 kWh = _________ J |
3.60 * 10^6 J |
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What is the first law of thermodynamics? |
Law of energy conservation: the total energy of the universe is constant |
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Define internal energy |
the sum of the kinetic and potential energies of all of the particles that compose the system -state function |
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Define state function |
its value depends only on the state of the system, not on how the system arrived at the state - specified by parameter such as temp, pressure, concentration, and physical state |
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Delta E = E final - E initial which is also what? |
E products - E reactants |
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Delta E system = ? |
- Delta E surroundings |
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Energy flowing out of a system is like a _____________. ( ? sign) |
withdrawal (- sign) |
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Energy flowing into a system is like a __________. (? sign) |
deposit (+ sign) |
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What is the official equation for delta E? |
Delta E = q + w |
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Define thermal equilibrium |
the heat transfer to the surroundings stops when the two reach the same temp -no additional net transfer of heat |
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What is the equation to find q? |
q = m * Cs * delta T |
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Define heat capacity |
a measure of the system's ability to absorb thermal energy without undergoing a large change in temp |
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Define extensive property |
it depends on the amount of matter being heated |
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Define Specific heat capacity (Cs) |
the amount of heat required to raise the temp of 1 gram of a substance by 1 degree C -sometimes reported as molar heat capacity |
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What are the units of specific heat capacity? |
J/g * degree C |
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Define molar heat capacity |
the amount of heat required to raise the temp of 1 mole of a substance by 1 degree C |
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What are the units of molar heat capacity? |
J/mol * degree C |
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Specific heat and molar heat are what kind of property? |
Intensive properties |
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Define intensive properties |
they depends on the kind of substance being heated, not on the amount |
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Define pressure-volume work |
occurs when the force is cause by a volume change against an external pressure |
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1 L * atm = __________ J |
101.3 J |
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Equation for pressure-volume work |
w = -P * delta V |
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Define Calorimetry |
we measure the thermal energy exchanged between the reaction (defined as the system) and the surroundings by observing the change in temp of the surroundings |
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Delta E reaction = q as long as what? |
volume is constant |
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Given w = 0, an endothermic reaction has what? |
+ delta H and - delta E |
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Define the bomb calorimeter |
a piece of equipment designed to measure delta E for combustion reactions |
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What are the q cal equations and the relative equations? |
q cal = C cal * delta T q cal = -q reaction in kJ
Delta E reaction = q reaction/mol |
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Define Enthalpy (H) |
the sum of its internal energy and the product of its pressure and volume |
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What is the equation for delta H? |
Delta H = delta E + P * delta V |
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Will an endothermic reaction be a +delta H or a -delta H? |
+ delta H |
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Will an exothermic reaction be a +delta H or a -delta H? |
- delta H |
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Define coffee cup calorimeter |
consists of two styrofoam coffee cups, one inserted into the other to provide insulation from the lab environment |
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Three quantitative relationships between a chemical equation and delta H reaction: |
1) If a chemical equation is multiplied by some factor, then delta H reaction is also multiplied by the same factor. A + 2B --> C delta H1 2A + 4B --> delta H2 = 2 * delta H1 2) If a chemical equation is reversed, then delta H reaction changes sign A + 2B --> C delta H1 C --> A + 2B delta H2 = - delta H1 3) If a chemical equation can be expressed as the sum of a series of steps, then delta H reaction for the overall equation is the sum of the heats of reactions for each step - Hess's Law A + 2B --> C delta H1 C --> 2D delta H2 ______________________ A + 2B --> 2D delta H3 = delta H1 + H2 |
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What are the three standard states and standard enthalpy changes parts? |
1) Standard State 2) Standard Enthalpy Change 3) Standard Enthalpy of Formation |
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What is the standard state for a gas? |
the standard state for a gas is the pure gas at a pressure of exactly 1 atm |
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What is the standard state for a liquid or solid? |
the standard state for a liquid or a solid is the pure substance in its most stable form at a pressure of 1 atm and at the temp of interest (often taken to be 25 degrees C) |
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What is the standard state for a substance in solution? |
the standard state for a substance in solution is a concentration of exactly 1 M |
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Describe the standard enthalpy change |
The change in enthalpy for a process when all reactants and products are in their standard states. The degree sign indicates standard states. |
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Describe the standard enthalpy of formation for a pure compound |
The change in enthalpy when one mole of the compound forms form its constituent elements in their standard states |
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Describe the standard enthalpy of formation for a pure element |
For a pure element in its standard state: delta H final = 0
elements --> compound delta H compound --> elements -delta H |