Chapter Ten Chemistry

solid to liquid

melting

solid to liquid to gas

melting then evaporation

gas to solid

deposition

Phase diagram

A - triple point B - melting/ freezing point C - evaporation/ condensation point D - critical temperature

State the five basic assumptions of the kinetic - molecular theory

1. Gases consist of large numbers of tiny particles that are far apart relative to their size 2. Collisions between gas particles and container walls are elastic collisions 3. Gas particles are in continuous, rapid, and random motion. They therefore possess kinetic energy, which is energy in motion 4. There are no forces of attraction between gas particles 5. The temperature of a gas depends on the average kinetic energy of the particles of gas

Phase Diagram

A --> highest temperature a chemical can exist as a liquid D --> the temperature and pressure combination at which a chemical can exist as a solid, liquid, and gas at the same time

What is the boiling point of a liquid?

A liquid boils at a temperature at which its vapor pressure is equal to the pressure of the gas above it. The lower the pressure of a gas above a liquid, the lower the temperature at which the liquid will boil. Water boils at exactly 100 degrees celsius

Properties of a liquid

A liquid can be described as a form of matter that has a definite volume and takes the shape of its container. The properties are relatively high density, relative incompressibility, ability to infuse, surface tension, and ability to evaporate.

What is an ideal gas?

An ideal gas is a hypothetical gas that perfectly fits all the assumptions of the kinetic - molecular theory

Using the phase diagram for CO2, describe all the phase changes that would occur when CO2 is heated from -100 degrees Celsius to -10 degrees Celsius at a constant pressure of 6 atm.

CO2 would melt into a liquid and then evaporate into a gas.

Compare and Contrast the four types of crystals

Covalent, Metallic, and ionic crystals have high melting points and densities. Molecular crystals tend to be soft and have lower melting points.

What is diffusion? What factors affect the rate of diffusion of one gas through another?

Diffusion is the spontaneous mixing of particles caused by their random motion. The rate is depended on the temperature and mass of particles.

What happens to gas particles when a gas is compressed?

Gas particles which are initially very far apart are crowded closer together.

Use the Kinetic theory to explain fluidity.

Gases do not have a definite shape or volume. Gas particles glide easily past one another. This ability to flow cause gases to behave as liquids do.

Difference between the way solids, liquids, and gases move

Gases vibrate and move freely at high speeds Liquids vibrate , move about, and slide past each other. Solids vibrate but generally do not move from place to place.

Describe the conditions under which a real gas is most likely to behave ideally

Ideal gases do not actually exist, many gases behave nearly ideally if the pressure is not very high and the temperature is not very low (or if it's a polar gas)

What is the difference between an amorphous solid and a crystalline solid?

In a crystalline solid the molecules are lined up in a very particular order. In an amorphous solid the molecules are not in a particular order.

What is sublimation? Give two examples of common substances that sublime at ordinary temperatures.

Sublimation is the change from a solid directly to a gas. Two common substances that sublime at common temperature are dry ice and iodine.

What is surface tension?

Surface tension is a force that tends to pull adjacent parts of a liquid's surface together, thereby decreasing surface area to the smallest possible.

What happens to gas particles when a gas is heated?

The average speeds and kinetic energies of gas particles increase with an increase in temperature and decrease with a decrease in temperature.

Use the Kinetic theory to explain low density.

The reason is that the particles are so much farther apart in a gaseous state.

Describe the structure of a water molecule.

Two hydrogen atoms join with an oxygen atom by a single covalent bond. Water is a polar covalent compound with a 105 degree bond angle.

List at least eight physical properties of water.

Water is transparent, odorless, tasteless, and almost colorless. Water has a high boiling point, surface tension, adhesion, cohesion, and polarity.

What is equilibrium?

a dynamic condition in which two opposing changes occur at equal rates in a closed system.

Account for each of the following properties of solids: a) the definite volume, b) the relatively high density of solids, c) the extremely low rate of diffusion

a) Solids have a definite volume because the Kinetic Molecular Theory states that particles in matter are always in motion, and since the particles in solids are so closely packed together, they are incompressible and therefore the shape of a solid doesn't depend on the shape of it's container. b) The relatively high density of solids result from the fact that particles of solids are more closely packed than those of a liquid or gas, as the Kinetic Molecular Theory states. c) Diffusion occurs in solids. The rate of diffusion is millions of times slower in solids than in liquids

endothermic

add energy

gas to liquid

condensation

liquid to gas

evaporation

liquid to solid

freezing

Use the kinetic theory to explain expansion.

gas particles move more rapidly in all directions, with no significant attraction between them

Use the Kinetic theory to explain compressibility.

gas particles which are initially very far apart are crowded close together.

How does the kinetic - molecular theory explain relatively high density?

particles are close together

How does the kinetic - molecular theory explain the ability to diffuse?

particles in a liquid are able to move in a confined space

How does the kinetic - molecular theory explain the ability to evaporate?

particles in a liquid are moving in a wide range of speeds. Liquids can escape the surface and evaporate into a gas.

exothermic

remove or lose energy

Use the Kinetic theory to explain diffusion.

spontaneous mixing of the particles of two substances caused by their random motion.

solid to gas

sublimation