Chapter 3

phase change

A change from one state (solid or liquid or gas) to another without a change in chemical composition example: water > vapor page: 84

A hazardous chemical is leaking from a tank truck. Rescue workers need to evacuate people who live near the accident. Why are more people likely to be affected if the chemical is a gas, rather than a liquid?

A gas can spread throughout the air and can spread much faster than a liquid. example: liquids spread much slower than gasses page: n/a

What is necessary phase change to occur? What are the 5 phases or states of matter? Explain the process of changing 3 of the 5 phases of matter discussed in class to undergo endothermic/exothermic phase changes.

A phase change is the reversible physical change that occurs when a substance changes from one state of matter to another. Solids, liquids, gasses, Bose-Einstein condensates, and vapors. example: there are 6 main phase changes page: 84

charles's law

A principle that describes the relationship between the temperature and volume of a gas at constant pressure example: temperature and volume remain the same page: 78

gas

A state of matter that does not have a definite volume or shape. example: water vapor page: 70

solid

A state of matter that has a definite shape and volume. example: ice cubes page: 69

liquid

A state of matter that has a definite volume but no definite shape. example: water page: 69

heat of fusion

Amount of energy required to change a substance from the solid phase to the liquid phase. example: tension releases when ice turns into water page: 86

Explain why this image represents Boyle's Law.

As the pressure increases, the volume decreases. As the pressure decreases, the volume increases. example: Boyle's Law states that the volume of a gas is inversely proportional to its pressure if the temperature and the number of particles are constant page: 79

Explain why this image represents Charles' Law.

As the temperature increases, the volume of the balloon increases. example: Charles's law states that the volume of a gas is directly proportional to its temperature in kelvins if the pressure and the number of particles of the gas are constant page: 78

boyle's law

At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure. example: when the volume goes up, the pressure goes down; when the volume goes down, the pressure goes up page: 79

Explain the relationship of between volume and pressure. Which law is it?

Boyle's Law states that the volume of a gas is inversely proportional to its pressure if the temperature and the number of particles are constant example: the temperature and pressure stay the same page:79

condensation

Change in state from a gas to a liquid example: water vapor > water page: 90

deposition

Change in state from a gas to a solid example: water vapor > ice page: 91

vaporization

Change in state from a liquid to a gas example: water > water vapor page: 88

evaporation

Change in state from a liquid to a gas example: water > water vapor page: 89

boiling

Change in state from a liquid to a gas example: water > water vapor page: n/a

freezing

Change in state from a liquid to a solid example: water > ice page: 88

sublimation

Change in state from a solid to a gas example: ice > water vapor page: 91

melting

Change in state from a solid to a liquid example: ice > water page: n/a

Explain the relationship of temperature and pressure. Which law is it?

Charles's law states that the volume of a gas is directly proportional to its temperature in kelvins if the pressure and the number of particles of the gas are constant example: when the volume goes up, the pressure goes down; when the volume goes down, the pressure goes up page:78

endothermic

Energy is absorbed from its surroundings. example: ice > water is an endothermic change page: 86

exothermic

Energy is released to its surroundings. example: wax melting is an exothermic change page: 86

kinetic energy

Energy that an object has due to its motion. example: x-rays page: 71

pressure

Force per surface area where the force is normal to the surface: measured in pascals example: pushing down on a water bottle page: 75

What is the difference between melting and freezing? At what temperature does water melt or freeze? What's the difference? Are there any other processes that act similarly?

Melting is from solid to liquid. Freezing is from liquid to solid. 0 degrees C is the freezing point. 100 degrees C is the melting point. example: ice > water is melting, water > ice is freezing page: n/a

Which phase changes are endothermic? Exothermic?

Melting, evaporation, and sublimation are endothermic. Deposition, condensation, and freezing are exothermic. example: these are the 6 types of phase changes page: 84

What are the 3 factors that affect gas pressure? Explain each (see pg. 76 and 77).

Temperature: raising the temperature of a gas will increase its pressure if the volume of the gas and the number of particles are constant Volume: reducing the volume of a gas increases its pressure if the temperature of the gas and the number or particles are constant Number of Particles: increasing the number of particles will increase its pressure if the volume of the gas and the number of particles are constant example: gas either increases or decreases pressure page: 76 and 77

heat of vaporization

The amount of energy required for the liquid at its boiling point to become a gas example: the temperature it takes for water to turn into water vapor page: 88

absolute zero

The coldest temperature, 0 Kelvin, that can be reached. It is the hypothetical temperature at which all molecular motion stops. example:ice freezes at absolute zero page: 78

How can the mass of a pile of snow decrease on a sunny day when the air temperature does not rise above 0 degrees C?

The heat from the sun can melt the snow. example: if there was no sun, the snow wouldn't have melted as quickly. page: n/a

What is the kinetic theory of gases?

The kinetic theory explains the general properties of a gas. o Particles in a gas are in constant, random motion. o The motion of one particle is unaffected by the motion of other partiles unless the particles collide. o Forces of attraction among particles in a gas can be gnored under ordinary conditions. example: this theory only works for gasses page: n/a

What is the kinetic theory of matter?

The kinetic theory of matter says that all particles of matter are in constant motion. example: all types of matter are always moving page: n/a

vapor pressure

The pressure exerted by the vapor which sits on top of any liquid example: increases as temperature increases page: 89

Be able to solve Combined Gas Law problems: P1V1/T1 = P2V2/T2 A gas is stored at constant volume at a pressure of 137kPa at 274K. If the temperature rises to 296 K, what is the pressure?

The pressure is 148 kPa example: the volume wasn't needed to solve this problem. page: n/a

Draw the motion of particles in a solid, liquid and gas as if you could see them under a microscope.

example: the particles in a solid are the tightest together page: 69