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