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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

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

Formula for pressure

P = F/A

What happens to the pressure when altitude increases?

Pressure decreases

Name common units of pressure

mmHg - often called a torr



atm



pascal (Pa)



in Hg



psi

Define atmosphere

the average pressure at sea level

Define barometer

an evacuated glass tube, tip is submerged in a pool of Hg

1 atm = ________ torr

760 torr

1 Pa = __________ N/m squared

1 N/m squared

What is the SI unit for pressure?

Pascal

1 atm = ____________ Pa

101,325 Pa

1 atm = ___________ in Hg

29.92 in Hg

1 atm = __________ psi

14.7 psi

What is a way to measure pressure in a lab?

The manometer

Define a manometer

a U-shaped tube containing a dense liquid, usually Hg


- always measures pressure of the gas sample relative to atmospheric pressure

What are the Simple Gas Laws?

Boyle's Law


Charles Law


Avogadro's Law

Boyle's Law is related to?

Volume and Pressure

What is the relationship between Volume and Pressure? What law is it related to?

Inverse relationship; Boyle's Law

What is the formula between Pressure and volume??

P1V1 = P2V2

Charles Law involves what?

Volume and Temperature

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

What is considered absolute zero?

-273.15 degrees C

What is the formula between Volume and temp? What law is it related to?

V1 / T1 = V2 / T2



Charles Law

What does Avogadro's Law Involve?

Volume and Amount (in moles)

What is the relationship between volume and amount (in moles)?

As volume goes up, amount in moles goes up


because they are directly proportional

What is the formula between Volume and amount in moles?



What law is it related to?

V1 / n1 = V2 / n2



Avogadro's Law

What is the Ideal Gas Law?

PV = nRT



R = ideal gas constant = 0.08206 L * atm / mol * k

As temp of a fixed amount of gas in a fixed volume increases, pressure ____________.



What is this called?

increases



gay-lussac's law

What is gauge P?

the difference between total P and atmospheric P

Define Molar V

the volume occupied by one mole of a substance

Standard temp:

0 degress C or 273 k

Standard P:

1 atm

Molar V at STP:

22.4 L

What is the formula for density?

Molar mass / Molar Volume



moles / liters

d = ?

PM / RT

What is the composition of air?

- Nitrogen 78%


- Oxygen 21%


- Argon 0.9%


- CO2 0.04%

Define Partial Pressure

the P due to any individual component in a gas mixture (Pn)

Formula for partial pressure

(Pn) = n * RT/V

What is Dalton's Law of partial pressures?

Sum of partial pressures:


P total = P(a) + P(b) + P(c) + ........

Mole fraction:

x(a) = n(a) / n(total)



or



P(a) = x(a) * P(total)

Define hypoxia

low oxygen levels produce the psychological condition ~ oxygen starvation

Define oxygen toxicity

increased oxygen concentration in the body tissues

Define Nitrogen narcosis

increased P(N2) beyond 4 atm in the body tissues ~ rapture of the deep



-often happens to divers

Define Vapor P

the partial P of water in the mixture


- increases with increasing temp

What is the partial pressure of H2O?

23.78 mmHg (its vapor P at 25 degrees C)

What is the Kinetic Molecule Theory

the simplest model for the behavior of gases

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

What is the formula for Kinetic Energy?

KE = 1/2 m v^2

What is the formula for KE (avg)?

KE(avg) = (3/2)RT

What is the formula for the root mean square velocity?

U(rms) = square root of 3RT/M



M must be in kg/mol

Define the Mean Free Path

the average distance that a molecule travels between collisions


- increasing with decreasing temp

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

Define Effusion

the process by which the gas escapes from a container into a vacuum through a small hole

What is the formula for Grahams law of effusion?

rate a


______ = square root of M b / M a


rate b ^molar masses

What is Waal's corrected ideal gas equation?

V = nRT + n*b



n = # of moles


b = constant that depends on the gas

Define Intermolecular Forces

attractions between the atoms or molecules that compose any substance

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

What is the total Van der Waals Equation?

[P + a (n/v)^2]*[V - n*b] = nRT

What is the equation for Real Gases?

PV/RT

Define Thermochemistry

the study of the relationships between chem and energy

Definition of exothermic

releasing heat

Definition of endothermic

absorbing heat

Define energy

capacity to do work

Define work

the result of a force acting through a distance

Define heat

the flow of energy caused by a temp difference

Define Kinetic Energy

the energy associated with the motion of an object

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

Define PE

the energy associated with the position or composition of an object

Define chemical energy

the energy associated with the relative positions of electrons and nuclei in atoms and molecules


- form of PE

What does the law of conservation of energy state?

That energy can neither be created nor destroyed

In an energy exchange, where is energy transferred?

Between the system and the surroundings

What are the units of energy?

Joules



cal



Cal

What does 1 Joule break down to?

1 J = kg * m^2/s^2

1 Cal = _______ cal

1 Cal = 1 kcal = 1000 cal

1 cal = ________ J

4.184 J

1 kWh = _________ J

3.60 * 10^6 J

What is the first law of thermodynamics?

Law of energy conservation: the total energy of the universe is constant

Define internal energy

the sum of the kinetic and potential energies of all of the particles that compose the system


-state function

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

Delta E = E final - E initial


which is also what?

E products - E reactants

Delta E system = ?

- Delta E surroundings

Energy flowing out of a system is like a _____________. ( ? sign)

withdrawal (- sign)

Energy flowing into a system is like a __________. (? sign)

deposit (+ sign)

What is the official equation for delta E?

Delta E = q + w

Define thermal equilibrium

the heat transfer to the surroundings stops when the two reach the same temp


-no additional net transfer of heat

What is the equation to find q?

q = m * Cs * delta T

Define heat capacity

a measure of the system's ability to absorb thermal energy without undergoing a large change in temp

Define extensive property

it depends on the amount of matter being heated

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

What are the units of specific heat capacity?

J/g * degree C

Define molar heat capacity

the amount of heat required to raise the temp of 1 mole of a substance by 1 degree C

What are the units of molar heat capacity?

J/mol * degree C

Specific heat and molar heat are what kind of property?

Intensive properties

Define intensive properties

they depends on the kind of substance being heated, not on the amount

Define pressure-volume work

occurs when the force is cause by a volume change against an external pressure

1 L * atm = __________ J

101.3 J

Equation for pressure-volume work

w = -P * delta V

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

Delta E reaction = q as long as what?

volume is constant

Given w = 0, an endothermic reaction has what?

+ delta H and - delta E

Define the bomb calorimeter

a piece of equipment designed to measure delta E for combustion reactions

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

Define Enthalpy (H)

the sum of its internal energy and the product of its pressure and volume

What is the equation for delta H?

Delta H = delta E + P * delta V

Will an endothermic reaction be a +delta H or a -delta H?

+ delta H

Will an exothermic reaction be a +delta H or a -delta H?

- delta H

Define coffee cup calorimeter

consists of two styrofoam coffee cups, one inserted into the other to provide insulation from the lab environment

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

What are the three standard states and standard enthalpy changes parts?

1) Standard State


2) Standard Enthalpy Change


3) Standard Enthalpy of Formation

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

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)

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

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.

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

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