(3)States and Types of Matter

In order to transition from one form of matter to the next…

A substance must either absorb or liberate heat

What is heat of fusion?

-The amount of heat that needs to be absorbed to convert 1 gram of a solid to 1 gram of the liquid at that substance’s melting point
-Measuerd in calories per gram
-80 calories of heat must be absorbed to change 1 gram of solid water to 1 gram of liquid water at 0 C

What is heat of vaporization?

-The amount of heat necessary to change 1 gram of a substance from the liquid to the gaseous state at the boiling point
-Water requires 540 calories of heat at the boiling point to become a gas

What is an exothermic reaction?

Processes that liberate heat

What is an endothermic reaction?

Processes that absorb heat

What is sublimation?

-The changing in state by which a substance passes directly from a solid state to a gaseous state
-Because the chemical composition doesn’t change, this is a physical change

What is entropy?

-The measure of the amount of disorder, or randomness of a substance
-Solids, being the most stable form of matter, have the least entropy while gases have the most

Gases are…

Compressible, expansive and diffusible

WHat is compressibility?

A property of gas involving the ability of the volume of a substance to be decreased by increasing the pressure on the gas

What is expansivity?

A property of gas involving the ability of the volume of a substance to be increased when heated

What is diffusibility?

A property of gas involving movement of a gas when introduced into a container

What is pressure?

Force per unit area

How is pressure measured?

-by a mercury barometer and expressed in millimeters of mercury or torrs
-if measured at sea level at a latitude of 45C, the mercury column supported by the pressure of the atmosphere is 760mm (this is referred to as 1 atmosphere, or 760 torr)
-Pressure varies with distance above sea level and climactic changes

Boyle’s Law

The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged in a closed system

Charle’s Law

when the pressure on a sample of dry gas is held constant, the Kelvin temperature and the volume will be directly related

What are the characteristics of liquid?

-When the pressure ona gas is increased or the temperature is lowered, gases will change to a liquid state
-Free space between liquid particles is minimal which makes them incompressible
-They maintain their own vilume
-When added to another liquid without agitation, liquids diffuse very slowly

What is evaporation?

-When particles near the surface of a liquid obtian enough energy to overcome the attractive forces between them, they change to a gaseous state
-Accompanied by a cooling of the particles remaining in a liquid state

What is equilibrium vapor pressure?

-Pressure exerted by a vapor when it is in equilibrium with its liquid
-as the temp increases, the vapor pressures of liquids increase

What is the boiling point?

Temp in which a liquid boils- at this temp, the vapor pressure of a liquid is equal to the pressure of the atmosphere on the liquid

What are the characteristics of solids?

-Particles are held tightly to one another by some type of bond
-Have a definite shape and volume
-nearly incompressible and do not expand significantly with increasing pressure
-Particles arent motionless
-May break apart when heat is added (melting)

What is heat of fusion?

If heat is applied to a solid that is under the melting point, it will absorb the heat and increase in temperature until it reaches the melting point

Elements are the basic

units of matter

How many elements are there?

-118 on the periodic table
-92 naturally occuring

What are the most abundant elements?

-On earth, oxygen and silicon secondly
-Hydrogen is the most abundant in the universe, second is helium

What are compounds?

-those formed when elements chemically join together in a definite proportion by mass

What is the law of definite proportions?

when 2 or more elements combine, they always comvine in a fixed or definite proportion by mass

What are heterogenous mixtures?

Mixtures easily separated by physical means. Constituent elements are visibly different

What are homogenous mixtures?

Mixtures which require a physical change to occur (ex: evaporation). Constituent elements appear uniform throughout.