States of Matter (chapter 13)
How many atm is 33.7 kPa?
.33 atm
How many atm is 385mmHg?
.507 atm
What are the three assumptions of the kinetic theory as it applies to gases?
1. The particles in a gas are considered to be small, hard spheres with an insignificant volume 2. The motion of the particles in a gas is rapid, constant, and random 3. All collisions between particles in a gas are perfectly elastic
___ atm= ____ mmHg= ____ kPa= 760 torr = 101,325 Pa= 101,325 N/m^2= 14.7 psi= 1013.25 mbar
1/760/101.3
At what temperature would water boils at the top of a mountain where the atmospheric pressure is 40 kPa?
33 degrees C
What atmospheric pressure would be needed for water to boil at 80 degrees C?
55 kPa
What is the boiling point of chloroform at standard pressure?
60 degrees C
Why is the entire flask filled with bromine?
A gas fills all the available space in its container
What is vapor pressure?
A measure of the force exerted by a gas above a liquid in a sealed container; a dynamic equilibrium exists between the vapor and the liquid.
What is a vacuum?
A space where no particles of matter exist and there is no pressure
What is the kinetic theory?
A theory explaining the states of matter based on the concepts that all matter consists of tiny particles that are in constant motion.
How are intermolecular forces in a liquid different from those in a gas?
According to the kinetic theory, there are no attractions between the particles in a gas. However, the particles in a liquid are attracted to each other. These intermolecular forces keep the particles in a liquid close together, which is why liquids have a definite volume.
The vapor pressures of ethanol are all higher than water. Relate this to how easy alcohol evaporates in comparison to water?
Alcohol evaporate much faster than water
What is a barometer?
An instrument used to measure atmospheric pressure
What does "equilibrium" mean?
At equilibrium, the particles in a system continue to evaporate and condense, but no net change occurs in the number of particles in the liquid or vapor.
How does the image of the early barometer in Figure 13.2 relate to the standard pressure of 760 millimeters if Mercury (or mmHg)? *
At sea level, the atmospheric pressure is higher because there are more collisions between particles, while the atmospheric pressure on top of Everest is much lower because the altitude is very high, so the density of Earth's atmosphere decreases and there are less collisions
Figure 13.3: The images are trying to convey that a solid (table salt), liquid (water), and gas (helium) all have the same _________ kinetic energy at the same temperature (20 C), even though the three substances are in different __________.
Average/physical states
Why do liquids evaporate faster when heated? (talk about molecules)
Because heating the liquids increase the average kinetic energy of its particles and the added energy enables more particles to overcome the attractive forces keeping them in the liquid state.
How does kinetic theory explain gas pressure?
Because the billions of rapidly moving particles in a gas simultaneously colliding with an object results in gas pressure.
Why does the question "What is the relationship between the temperature particles in kelvins and the average kinetic energy of particles?" specify kelvin?
Because the kelvin temperature scale reflects the relationship between temperature and average kinetic energy.
Why is it important to discuss the average kinetic energy of molecules in a substance?
Because the particles in any collection go atoms or molecules at a given temperature have a wide range of kinetic energies, but most have kinetic energies somewhere in the middle, so the average kinetic energy is used when discussing the kinetic energy of a collection go particles in a substance.
Under what conditions does boiling occur?
Boiling occurs when a liquid is heated to a temperature at which particles throughout the liquid have enough kinetic energy to vaporize, the liquid begins to boil.
How does the boiling point of a liquid (such as water) change when you go to higher altitudes where atmospheric pressure is lower?
Boiling points decrease at higher altitudes because atmospheric pressure is lower at higher altitudes
What is water's freezing point (in C)? What about water's melting point?
Both0 degrees C
How does atmospheric pressure change with altitude?
Decreases as altitude increases- because the density of Earth's atmosphere decreases as the elevation increases, so the higher the altitude, the less collisions
What is the phase change that is the opposite if sublimation?
Deposition
What is an amorphous solid?
Describes a solid that lacks an ordered internal structure; denotes a random arrangement of atoms.
Solid carbon dioxide is also known as...
Dry ice
What is the relationship between evaporation and kinetic energy?
During evaporation, only those molecules with a certain minimum kinetic energy can escape from the surface of the liquid.
Exothermic or endothermic phase change: liquid to vapor
Endothermic
Exothermic or endothermic phase change: solid to liquid
Endothermic
Exothermic or endothermic phase change: solid to vapor
Endothermic
Is evaporating exothermic or endothermic? Why?
Endothermic because water molecules just absorb heat from the surroundings to increase their kinetic energy.
Exothermic or endothermic phase change: liquid to solid
Exothermic
Exothermic or endothermic phase change: vapor to liquid
Exothermic
Exothermic or endothermic phase change: vapor to solid
Exothermic
True/False: All substances in closed containers produce the same vapor pressure
False
True/False: At equilibrium, particles stop changing state
False
Gases and liquids move similarly, they are both fluids because they... *
Flow
What holds the particles in air within Earth's atmosphere?
Gravity
When can a dynamic equilibrium exist between a liquid and its vapor?
In a system at constant vapor pressure. The system is in equilibrium because the rate of evaporation of liquid equals the rate of condensation of vapor.
How does an increase in temperature affect a compound's ability to evaporate?
Increase in evaporation
How does a manometer work?
It measure vapor pressure. The vapor pressure is equal to the difference in height of the mercury in the tow arms of the u-tube.
What is an elastic collision?
Kinetic energy is transferred without loss from one particle to another, and the total kinetic energy remains constant
When a substance is heated, both _______ energy and _______ energy can increase. But only the increase in _______ energy causes the temperature of substance to increase.
Kinetic/potential/kinetic
At higher temperatures, [more/less] of the substance will exist in the gas phase at equilibrium.
More
How does the amount of energy to melt a given mass of ice compare to the energy required to vapor the same mass of liquid water? (which is harder to do?)
More energy to vaporize liquid water
The vapor pressures of ethanol are all higher than water. What does this say about the relative strength of attraction between particles of each substance?
Much weaker than water
Does the water level change over time in a sealed container? Why?
No. In a sealed container, the molecules cannot escape. They collect as vapor above the liquid and some molecules condense back into liquid.
What are allotropes?
One of two or more different molecular forms of an element in the same physical state; oxygen (O2) and ozone (O3) are allotropes of the element oxygen.
If not KE, what kind o energy must be increasing during the phase changes?
Potential energy
What is gas pressure? (P=F/area)
Results from the force entered by a gas per unit surface area of an object; due to collisions of gas particles with the object.
When can sublimation occur?
Sublimation occurs in solids with vapor pressures that exceed atmospheric pressure at or near room temperature
What is normal boiling point?
The boiling point of a liquid at a pressure of 101.3 kPa or 1 atm
Define vaporization
The conversion of a liquid to a gas to a vapor
Define kinetic energy: (KE= 1/2 mv^2)
The energy an object has because of its motion
How are the structure and properties of solids related?
The general properties of solids reflect the orderly arrangement of their particles and the fixed locations of their particles
What factors determine the physical properties of a liquid?
The interplay between the disruptive motions of particles in a liquid and the attractions among the particles determines the physical properties of liquids.
What is the relationship between the temperature particles in kelvins and the average kinetic energy of particles?
The kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles of the substance.
How much kinetic energy does a gas at 50K have relative to a gas at 200K?
The particles of gas at 200K have four times the average kinetic energy as the particles in the gas at 50K.
What is the triple point of a substance?
The point on a phase diagram that represents the only set if conditions at which all three phases exist in equilibrium with one another.
What is the STRICT definition of boiling point?
The temperature at which the vapor pressure of a liquid is just equal to the external pressure on the liquid
What is a glass?
Transparent fusion product of inorganic materials that have cooled to a rigid state without crystallizing.
True/False: Liquids are less dense than gases
True
True/False: Temperature remains constant during a phase change.
True
True/False: Vapor pressures are dependent on temperature
True
Give a precise definition of evaporation
Vaporization that occurs at the surface of a liquid that is not boiling
Why do we sweat? Why does it work?
We sweat because when you perspire, water molecules in your perspiration absorb heat from you body and evaporate from the skins surface. It works because it leaves the remains perspiration cooler and it absorbs your body heat, and cools the body.
In terms of particles, what happens when a substance is warmed to its melting point?
When you heat a solid, its particles vibrate more rapidly as their kinetic energy increases. The organization of particles within the solid breaks down, and eventually the solid melts.
Particles travel in ________________ between collisions
a straight-line path
As temperature increases, vapor pressure...
increases
Particles collide with ______________ and with the walls of a _________.
one another/container
