Chapter 7 Flashcards
Most of the elements in nature are _____ when isolated at room temperature.
solids
There are only 2 elements which are ______ at room temperature.
liquids
What are the 2 elements that are liquids at room temperature?
Hg (mercury) and Br (Bromine)
There are several elements which are _____ at room temperature.
gases
What are the elements that are gases at room temperature?
N (nitrogen), O (oxygen), F (Fluoride), Cl (Chloride), H (hydrogen), and all the noble gases
The _______ ______ ______ proposes that all particles making up a substance (atoms, molecules, and/or ions) are in constant random motion at all temperatures above absolute zero Kelvin.
kinetic molecular theory
____ is made up of tiny particles (atoms, molecules, ion) that have definite size and unalterable characteristics.
Matter
______ _____ is energy due to motion of matter.
Kinetic energy
Particles can transfer kinetic energy to on another through _____ _____ - like billiard balls.
elastic collision
______ _____ is stored energy due to position and composition.
Potential energy
______ ______ are attractions and repulsions of charged entities.
Electrostatic interactions
Particles interact with each other via _____ and _____.
attractions and repulsions
______ ______ are collisions where no kinetic energy is lost to the environment. That is, the sum of the kinetic energy of all participants prior to the collision equals the sum of the kinetic energies of all participants after the collision.
Elastic collisions
Particle speed of kinetic energy increases as the _____ is raised.
temperature
Kinetic energy is a ______ _____.
disruptive force
Potential energy is a _____ _____
cohesive force
When the temperature of a system is raised, the _____ _____ of the particles in the system increases.
kinetic energy
What is the mathematical expression of kinetic energy?
1/2mv^2
The ______ component is a squared factor in kinetic energy.
velocity
In the _____ _____ potential energy (cohesive forces) dominates over kinetic energy (disruptive forces).
solid state
Solids are ____ and have ____ ____ because the strong cohesive forces keep the particles in fixed positions.
rigid; fixed volumes
Solids have ____ _____.
high density
With water ___________, solids are usually denser than their corresponding liquid phase.
being a major exception
Due to the compact and orderly packing of particles in a solid, there is virtually no empty space between particles. Consequently, there is hardly any empty space that can be eliminated by increasing the pressure, and solids exhibit a very ____ _____.
low compessibility
Increasing the temperature increase kinetic energy (disruptive force). The particles will increase vibrational motion about their fixed positions.Thus, they will occupt somewhat more space. Consequently, a solid will exhibit a very _____ _____ _____ with increased temperature.
small thermal expansion
In a _____, the particles are randomly packed, but they are relatively close together.
liquid
The ____ _____ is the physical state in which neither force (disruptive, cohesive) dominates.The kinetic energy and the potential energy have similar magnitude and balance each other.
liquid state
Liquids exhibit both _____ and _____.
fluidity and cohesiveness
Liquids will assume any shape of any container that they can fill meaning they have _____________.
indefinite shape and definite volume
The particles in a liquid are packed together in such a way that they essentially touch one another but there is hardly any space between the particles. The high number of particles per unit volume causes liquids to have _____ _____.
high density
As the particles in a liquid are in physical contact, there is not much space in between them that can be eliminated by increasing the pressure on the system. The particles cannot be squeezed closer together, the __________ ___ ______.
compressibility is small
A liquid will exhibit a ____ ____ _____ with increased temperature.
small thermal expansion
In the _____ _____ the disruptive forces (kinetic energy) dominate over the cohesive forces (potential energy).
gaseous state
A sample of gas is totally flexible. It completely occupies any container in which it is placed and escapes into the atmosphere when released. Gases exhibit _____ shape and ______ volume.
indefinite (for both)
Because the particles are so far apart from each other, there is very little mass per unit volume. Therefore, gases have _____ _____.
low density
Gases are really mostly empty space. Consequently, a lot of this space can be eliminated by putting pressure on the system. Gases exhibit _____ ______. If sufficient pressure is applied, gas molecules are forced to com in contact with each other, and the gas liquefies.
large compressibility
When the temperature is increased, more kinetic energy is imported to the gas particles. The particles will have more velocity, resulting in more energetic collisions with the container walls, which will expand somewhat. Hence, the volume increases and gases exhibit ______ ______ ______.
moderate thermal expansion
_______ is a term that describes an exchange or energy. In the case of phase changes, this refers to a change of state that requires the input of heat energy.
Endothermic
Endo means _____ ____!
energy in
______, _______, and ______ are endothermic processes.
melting, evaporation and sublimation
_______ is a term that describes en exchange of energy. In the case of phase changes, this refers to a change of state that results in heat energy being released.
exothermic
Exo means ____ ____ (___)!
energy out (exit)
______, ______, and _____ are exothermic processes.
freezing, condensation and deposition
______ is the process by which a substance changes from the liquid to the gaseous state at a temperature below its boiling point.
Evaporation
The rate of evaporation of a liquid is dependent of 3 things:
- The _______ of the liquid;
- The ______ of the liquid;
- The ______ of the system.
surface area;
identity;
temperature
______ is a surface phenomenon. The molecules below the surface are “buried” and surrounded at all sides by other molecules that attract them. This makes their escape very unlikely.
Evaporation
The greater the ______ _____, the faster the process of evaporation.
surface area
As the molecules with higher kinetic energy evaporate, the average kinetic energy of the remaining molecules is inherently lower. The temperature of the remaining liquid decreases as the higher energy vapor molecules escape to the atmosphere. The process is called ______ ______.
evaporation cooling
Molecules that evaporate from a liquid are often referred to as ____ rather than a gas.
vapor
A _____ if the gaseous phase of a substance that is normally a liquid of a solid at the given temperature and pressure conditions.
vapor
Whenever the rates of two opposing processes are the same, we refer to this situation as a ___________________ or ____________.
steady-state condition or equilibrium
The vapor molecules in a closed system at equilibrium exert pressure on the container walls and the surface of the liquid. This pressure is referred to as the _____ _____.
vapor pressure
The _____ ____ is the pressure exerted by the vapor of the liquid above the body of the same liquid when the vapor and the liquid are in equilibrium.
vapor pressure
Vapor pressure depends on two things:
The ____ and the _____ _____ of the substance
temperature and chemical identity
The vapor pressure can easily be determined with a _______.
manometer
A _______ is a device that uses a mercury-filled U-tube connected to a closed container containing a small amount of the liquid of interest. The liquid is allowed to evaporated at a given temperature until it reaches equilibrium. The change in the level of the mercury in the U-tube is used to determine the pressure of the gas inside the container.
manometer
The atmosphere exerts pressure on the open end of the U-tube (_____ _____) while the gas exerts pressure on the opposite end (_____ _____).
right arm;
left arm
The gas pressure inside the container is given by:
P container + P atmosphere = delta P
The _____ of a liquid refers to its readiness to evaporate or from a vapor at a given temperature.
volatility
Chemicals with a high vapor pressure are said to be _______.
volatile
Chemicals with a ____ vapor pressure are said to be nonvolatile.
low
______ is a special case of vaporization where the change of phase (from the liquid to vapor) occurs throughout the body of the liquid. This process occurs only when the vapor pressure of the liquid is equal to the external atmospheric pressure.
Boiling
The ____ ____ of a liquid is defined as the temperature at which the boiling process takes place.
boiling point
The boiling point depends on two things:
The external pressure and the identity of the liquid.
The ____ ____ ____ is the temperature at which a liquid boils when exposed to an external pressure of 1 atm (atmosphere).
normal boiling point
1 atm is defined at the average _____ pressure at sea level.
barometric
The normal boiling point of water is ____ degrees Celcius.
100
At lower pressure, the vapor pressure decreases. Therefore, in a vacuum, the volatility of a liquid greatly increases. If a vacuum is applied to the container, we can boil water in the palm of our hand! This process is called _____ _____ and is used to make frozen fruit concentrates at low temperatures.
freeze drying
Chemists have identified 3 different types of interactions that occur among molecules called _____ ______ ______.
intermolecular attractive forces
- Dipole - dipole interactions
- Hydrogen bonds
- London forces or induced dipoles
______-______ _____ are electrostatic interactions among polar molecules. These interactions occur due to a positive and negative dipole in the molecules. Similar to a pair of magnets, the molecules involved in this type of interactions can attract each other or, if turned, repel each other.
Dipole - dipole interactions
____ _____ _____ are special electrostatic interactions among polar molecules that have the unique ability to form a special attraction to a hydrogen atom through a pair of lone (nonbonding) electrons. These interactions are generally much stronger than normal dipole-dipole interactions. However, only certain types of molecules can actually participate in this formation.
Hydrogen bond interactions
_____ _____ or _____ ____ are special electrostatic interactions among polar and nonpolar molecules. These dipoles are induced by the presence of another molecule and are the weakest of the intermolecular forces. These have low boiling points.
London forces or induced dipoles
____ ____ are simple mathematical equations that relate the pressure, temperature, volume, and amount of a gas to each other.
Gas laws
_____ is defined mathematically as the ratio of a force divided by the area of the surface to which the force is applied.
Pressure
The equation to find the pressure is:
Pressure (P) = Force (F) / Area (A)
If you decrease the force, the pressure _______.
decreases
If you decrease the area, the pressure ______.
increases
The molecules and atoms in the atmosphere exert pressure on all objects in the atmosphere. This pressure is called the _______ or _____ ______.
atmospheric or air pressure
1 ____ is defined as 1 mm Hg.
torr
______ or ______ is defined as the average barometric pressure at sea level.
1 atmosphere or 1 atm
1 atm = _____ or _____.
760 mm of Hg or 760 torr
Robert Boyle determined that the pressure and volume of gas are _____ ____, meaning that when either variable increases, the other decreases proportionally.
inversely proportional
_____ ____ states that there is an inverse relationship between the pressure and volume of a fixed mass of gas at constant temperature (in Kelvin).
Boyle’s law
When using any of the gas laws, the temperature must be expressed in _____ units.
Kelvin
Mathematically, Boyle’s law can be expressed as:
P1 (initial pressure) V1 (initial volume) = P2 (final pressure) V2 (final volume
_____ _____ states that the volume of a fixed mass of gas is directly proportional to its Kelvin temperature at constant pressure.
Charles’s law
Mathematically, Charles’s law can be expressed as:
V1 (initial volume) / T1 (initial temperature in K) = V2 (final volume) / T2 (final temperature in K)
____-_____ ____ states that the pressure of a fixed mass of gas is directly proportional to its Kelvin temperature at constant volume.
Guy-Lussac’s Law
Mathematically, Guy-Lussac’s law can be expressed as:
P1 (initial pressure) / T1 (initial temperature in K) = P2 (final pressure) / T2 (final temperature in K)
______ _____ states that at the same temperature and pressure, equal volumes of gases contain equal numbers of molecules. In other words, the volume of a gas is proportional to the number of molecules (moles) of gas present at constant temperature and pressure.
Avogadro’s law
Mathematically, Avogadro’s law can be expressed as:
V1 (initial volume) / n1 (initial number of molecules) = V2 (final volume) / n2 (final number of molecules)
If we combine Boyle’s, Charles’s, Guy-Lussac’s, and Avogadro’s law into ONE LAW, mathematically, it is expressed as:
P1V1 / T1n1 = P2V2 / T2n2
(initial pressure)(initial volume) / (initial temperature)(initial number of molecules) = (final pressure)(final volume) / (final temperature)(final number of molecules)
The ____ _____ and _____ (symbol ___) are defined values used as a reference for all scientists.
Standard Temperature and Pressure (STP)
The standard temperature or gas is ___ degrees Celcius or ____ Kelvin.
0 degrees C;
273 K
The standard pressure for gas is ___ atm or ____ mm Hg (torr).
1 atm;
760 mm Hg (torr)
The ____ ____ ____ describes the relationship among the four variables, pressure (P), volume (V), temperature (T), and moles of gas (n) for gases at one set of conditions.
ideal gas law
Mathematically, the ideal gas law can be expressed as:
PV = nRT (pressure)(volume) = (number of moles)(constant)(temperature)
The ____________ is the volume occupied by one mole of a gas. According to Avogadro’s law, this is the same for all gases at the same temperature and pressure, regardless of their chemical identity.
molar volume of gas
The molar volume of gas at STP equals _______.
22.414 L
The amount of gas at STP equals ______.
1 mole
The value given to R is ______ after using STP for P, V, n, and T.
0.0821
If torr if given, we can convert R to torr:
0.0821 x L atm / mole K x 760 torr / 1 atm = 62.4 L torr / mole K
__________ states that the total pressure of a mixture of gases is a summation of the partial pressure of all the gases present in the mixture.
Dalton’s law of partial pressure
Mathematically, Dalton’s law is expressed as:
P total = P1 + P2 + P3 + etc… OR
P total = n1RT / V + n2RT / V + n3RT / V + etc… OR
P total = n total x R x T / V
