Chemistry test 11
What is the angle between the bonds of a water molecule
105°
How many molecules are there per group in liquid water
4 - 8 molecules
What is the triple point in a phase diagram
A
A type of solid in which the particles are arranged randomly No distinct geometric shape
Amorphous solid
How is equilibrium vapor pressure affected by an increase or decrease in temperature
As temperature of a liquid increases, the equilibrium vapor pressure increases This energy change increases the number of liquid molecules that have enough energy to escape into the gas phase, increasing the number of molecules in the gas phase and increasing the equilibrium vapor pressure
What is the shape of a water molecule
Bent
The conversion of a liquid to a vapor within the liquid as well as its surface
Boiling
The attraction of the surface of a liquid to the surface of a solid
Capillary action
What is the second assumption of the kinetic molecular theory Explain
Collisions between gas particles are *elastic collisions* There's no net loss of total kinetic energy
Being able to squish particles into tighter spaces
Compressibility
A type of solid that consists of crystals: a substance in which the particles are arranged in an orderly, geometric, repeating pattern
Crystalline solid
Do crystalline and amorphous solids have definite melting points
Crystalline — definite melting points Amorphous — flow over a range of temperatures
What are the 3 properties of solids
Definite shape and volume Definite melting point High density and incompressibility
The degree of compactness of a substance Gases have lowest, solids have highest
Density
The change of state from a gas directly to a solid
Deposition
The ability of gases to mix evenly with particles of another gas
Diffusion
What is an example of sublimation
Dry ice
Process by which gas particles pass through a tiny opening
Effusion
A condition in which 2 opposing changes are occurring at equal rates in a closed system
Equilibrium
The pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature
Equilibrium vapor pressure
Gases don't have a definite shape or volume; therefore, gases completely full any container in which they're enclosed
Expansion
What are the 6 properties of gases
Expansion Fluidity Low density Compressibility Diffusion Effusion
How does the kinetic molecular theory account for a gas's ability to expand
Expansion occurs because gas particles move in all directions (3), without being attracted to other gas particles (4)
Gas particles slide easily past each other, behaving as liquids do
Fluidity
How does the kinetic molecular theory account for a gas's ability to be fluid
Fluidity is possible because there are no attractive forces between gas particles (4)
The physical change of a liquid to a solid
Freezing
What are 2 examples of deposition
Frost/snow formation Soot in a chimney
Does a solid lose or gain energy in the process of melting
Gain energy
When a substance freezes, does it gain order or lose order
Gain order (liquid —> solid)
What is the third assumption of the kinetic molecular theory Explain
Gas particles are in continuous, rapid, random motion Because of this, gas particles possess kinetic energy
How does the kinetic molecular theory account for a gas's low density
Gases aren't dense because gas particles are very far apart (1)
How does the kinetic molecular theory account for a gas's ability to be compressed
Gases can be compressed because gas particles are normally far apart (1). A gas in a large container can be compressed into a smaller container because gas particles have more room between each other. The gas particles would still fill the container, but would be closer to each other than in the larger container.
What is the first assumption of the kinetic molecular theory Explain
Gases consist of large numbers of tiny particles that are far apart relative to their sizes Certain number of gas particles can occupy much larger volumes of space than a liquid or solid with the same number of particles Most of the volume occupied by a gas is empty space and this is why gases are easily compressed or expanded & have lower densities than solid or liquid
How does the kinetic molecular theory account for a gas's ability to doffuse
Gases diffuse because of the random and continuous motion of gas particles (3) and because of the great amount of empty space between gas particles (1)
What is an example of an amorphous solid
Glass
How does an increase in pressure affect boiling point
Higher atmospheric pressure = higher boiling point
What causes water to be a liquid at room temperature instead of a solid
Hydrogen (hydrogen bonding)
What kind of bonds link solid and liquid water
Hydrogen bonding
What causes ice to float
Ice has water molecules arranged in a rigid, ordered, hexagonal pattern that leaves empty spaces between the molecules (low density) Hydrogen bonds in liquid are more disordered and can crowd closer together, causing liquid water to be more dense than solid water
A hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory
Ideal gas
Why is it important that ice floats on the liquid form of water
If I've didn't float, it would sink to the bottom of a body of water where it would be less likely to melt completely — eventually freezing the entire body of water & killing all living things
How does the arrangement of solid particles explain how solids have different properties than liquids and gases
Intermolecular forces are more effective in solids than in liquids or gases Intermolecular forces gave stronger effects on solids Attractive forces hold the particles of a solid in relatively fixed positions, with only vibrational moment around fixed points Because of this, solids are more ordered than liquids and much more ordered than gases
When a solid melts, does it become more ordered or less ordered
Less ordered (solid —> liquid)
A form of matter that has a definite volume and takes the shape of its container
Liquid
Why do liquids diffuse slower than gases
Liquid particles are closer together Because the attractive forces between liquid particles slow their movement
Why are liquids less compressible than gases
Liquid particles are more closely pack together
Why does evaporation occur
Liquid particles have different kinetic energies — particles with greater kinetic energy can overcome the intermolecular forces that bind them to a liquid and can enter the gas state
Why does capillary action occur
Liquid will rise in a very narrow tube against the flow of gravity if a strong attraction exists between the liquid molecules and the molecules that make up the surface of the tube
When a substance freezes, does the formation of the solid lead to a loss or gain of energy
Loss of energy
The reverse of freezing — a solid becomes a liquid
Melting
The amount of energy as heat required to melt one mole of a solid at the solid's melting point
Molar enthalpy of fusion
The amount of energy (heat) needed to vaporize one mole of a liquid at the liquid's boiling point at constant pressure
Molar enthalpy of vaporization
What is kinetic energy the energy of
Motion
What 2 types of gases act most like ideas gases
Noble gases (monatomic, nonpolar) Diatomic gases
Liquids that do not evaporate readily
Nonvolatile liquids
Why are solids incompressible
Particles of a solid are more closely packed than in liquids or gases
Why do solids have high density
Particles of a solid are more closely packed than in liquids or gases
How are the particles of a solid arranges in comparison to particles of a liquid and gas
Particles of a solid are more closely packed than liquids or gases
Any part of a system that has uniform composition and properties
Phase
A graph of pressure vs. temperature that shows the conditions under which the phases of a substance exist
Phase diagram
What is melting point
Physical change of a solid to a liquid by the addition of energy as heat — the temperature at which a solid becomes a liquid
What type of bonds make up a water molecule
Polar covalent bonds Hydrogen bonds
What are the 6 properties of liquids
Relatively high density Relative incompressibility Ability to diffuse Surface tension Evaporate and boiling Formation of solids
What are the 3 phases we discussed
Solid Liquid Gas
What causes a liquid to be nonvolatile
Strong attractive forces between particles
Why is boiling point & molar enthalpy of vaporization high in water
Strong hydrogen bonding that must be overcome
Why are liquids denser than gases
Stronger intermolecular forces and lower mobility of gas particles Close arrangement of liquid particles as compared to a gas
The change of state from a solid directly to a gas
Sublimation
A force that tends to pull adjacent parts of a liquid's surface together, thereby deciding surface area to the smallest possible size This is a result of attractive forces between liquid particles
Surface tension
What does line AD represent on a phase diagram
Temperature and pressure at which ice and liquid water coexist at equilibrium
What does line AB represent on a phase diagram
Temperature and pressure at which ice and water vapor occur at equilibrium
What does line AC represent on a phase diagram
Temperature and pressure at which liquid water and water vapor coexist at equilibrium
What 2 requirements are needed for equilibrium to occur
Temperature remains constant System stays closed
How does the arrangement of particles in a liquid explain how liquids have different properties than gases
The attractive forces between particles in a liquid are greeter than those in a gas (these are caused by intermolecular forces) Liquids are more ordered than gases because of stronger intermolecular forces and lower mobility of liquid particles
If a substance has strong intermolecular forces, will it have a high enthalpy of vaporization or a low one? Explain.
The enthalpy of vaporization will be high because the stronger the attraction between particles, the more energy that is required to overcome the attraction, and the higher the molar enthalpy of vaporization
What is the kinetic molecular theory based on
The idea that particles of matter are always in motion
What determines how easy it is to melt something
The level of attraction between solid particles
How are the particles of a liquid arranged compared to a gas and a solid
The particles are in constant motion, just like a gas and a solid Liquid particles are closer together than gas particles, but further away than solid particles
Why is the temperature of a boiling liquid constant
The pressure is constant All the extra energy is being used to overcome the attractive forces of the liquid beyond the boiling point temperature
How does the kinetic molecular theory account for a gas's ability to effuse
The rates of effusion of different gases are directly proportional to the velocities of their particles, so molecular with low mass will effuse faster than molecules of high mass (5)
What is the fifth assumption of the kinetic molecular theory Explain
The temperature of a gas depends on the average kinetic energy of the particles of the gas Average speeds of gas particles increase with an increase in temperature At the same temperature, lighter gas particles would have higher average speeds than heavier gas particles KE = 1/2•m•v (m=mass) (v=speed)
Why do solids have a definite shape and volume
Their particles are packed closely together and there's very little empty space into which solid particles can be compressed
What is the fourth assumption of the kinetic molecular theory Explain
There are no forces of attraction between gas particles When gas particles collide, they immediately bounce away from each other
Why are amorphous solids sometimes called supercooled liquids
They can retain certain liquid properties even at temperatures at which they appear to be solid (due to random arrangement of particles)
What is the difference between evaporization, vaporization, and boiling
Vaporization — the process by which a liquid or solid changes to a gas Evaporation — the process by which particles escape from the surface of a nonboiling liquid and enter the gas state (form of vaporization) Boiling — the change of a liquid to bubbles of vapor that appear throughout the liquid
At what conditions does a gas deviate from ideal behavior
Very high pressures Low temperatures
Liquids that evaporate readily
Volatile liquids
What causes a liquid to be volatile
Weak attractive forces between their particles
How does sweat cool us
When water vaporizes, it carries a lot of heat away from the skin
Do solids diffuse
Yes Millions of times slower than in liquids