# Matter: Properties & Change

## Presentation on theme: "Matter: Properties & Change"— Presentation transcript:

Matter: Properties & Change

Physical properties Physical properties can be observed or measured without changing the identity of the matter. Basically, properties you notice when using one of your five senses: Feel - mass, volume, texture Sight - color Hear Smell Taste

Physical properties of matter are categorized as either: Intensive or Extensive:
Intensive - Properties that do not depend on the amount of the matter present. Color Odor Luster - How shiny a substance is. Malleability - The ability of a substance to be beaten into thin sheets. Ductility - The ability of a substance to be drawn into thin wires.

Conductivity - The ability of a substance to allow the flow of energy or electricity.
Hardness - How easily a substance can be scratched. Melting/Freezing Point The temperature at which the solid and liquid phases of a substance are in equilibrium at atmospheric pressure. Boiling Point - The temperature at which the vapor pressure of a liquid is equal to the pressure on the liquid (generally atmospheric pressure).

More Physical Properties
Density is a very important property. It is the amount of matter in a given volume. Density = Mass / Volume

A. Physical Properties Physical properties can be described as one of 2 types: Extensive Property depends on the amount of matter present (example: length) Intensive Property depends on the identity of substance, not the amount (example: scent)

B. Extensive vs. Intensive
Examples: boiling point volume mass density conductivity intensive extensive

Extensive - Properties that do depend on the amount of matter present.
Volume - A measurement of the amount of space a substance occupies. *Length

V is for Volume Briefly, volume is the amount of space something takes up. Whether it’s a speck of dust or Jupiter, all matter takes up space.

Measuring the volume of…
Liquids: Graduated cylinder Displacement method Measured in liters (L) & milliliters (mL) Solids: Length x width x height Gases: Since a gas expands to fill its container, if you know the volume of the container, you know the volume of the gas.

Density - The mass of a substance divided by its volume
Density is an important physical property. Density is the mass of a substance per unit volume. Volume is the amount of space an object occupies.

C. Density – a physical property
Derived units = Combination of base units Volume (m3 or cm3 or mL) length  length  length Or measured using a graduated cylinder 1 cm3 = 1 mL 1 dm3 = 1 L Density (kg/m3 or g/cm3 or g/mL) mass per volume D = M V

C. Density V = 825 cm3 M = DV D = 13.6 g/cm3 M = (13.6 g/cm3)(825cm3)
An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: V = 825 cm3 D = 13.6 g/cm3 M = ? WORK: M = DV M = (13.6 g/cm3)(825cm3) M = 11,220 g M = 11,200 g

C. Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL
A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? M = 25 g WORK: V = M D V = 25 g 0.87 g/mL = mL V = 29 mL

Physical Properties - Examples
Other physical properties include: Color Hardness Odor Taste State of matter Texture Luster (shine) Flexibility Heat conductivity Electrical conductivity Solubility (ability to dissolve in water.) Shape Viscosity Ductility Malleability

D. Chemical Properties Chemical Property
describes the ability of a substance to undergo changes in identity

Chemical properties A common chemical property is reactivity.
Reactive to oxygen Reactive to air Reactive to water… Notice that chemical properties aren’t EASY to observe, unlike physical properties.

Chemical properties - Examples
Examples of chemical properties include: The ability to burn Ability to tarnish Ability to rust Ability to decompose Ability to react with other chemicals Instability Ability to do acid/base reactions

Physical vs. Chemical Physical properties: observe without changing the identity of the substance Chemical properties: observe only when the identity changes How do you know if it is chemical or physical? If it CHanges, it’s CHemical

E. Physical vs. Chemical Properties
Examples: melting point flammable density magnetic tarnishes in air physical chemical

Chemical and physical properties – So what?
Titanium is very strong and doesn’t rust, so it is often used in jet engines. Titanium is also nonallergenic. This, combined with the fact that it is rust proof makes it great for artificial joints as well as piercings.

Chemical and physical properties – So what?
Tungsten is usually used as the filament in lightbulbs because it has the highest melting point of any metal. It glows red hot when electricity runs through it, and it gives off both heat and light.

Chemical and physical properties – So what?
Vanadium is heavier and harder than titanium, so mixing a tiny bit of vanadium with steel can make cheap tools that are still very strong.

Chemical and physical properties – So what?
Helium is almost completely nonreactive (inert). It is lighter than air, so it’s great for floating balloons (or making funny voices.) When electricity runs through helium, it glows a creamy pale peach color.

Chemical and physical properties – So what?
In 1943, all US pennies were made of zinc plated steel because copper was being used in the war. The pennies had to be coated with zinc because steel will rust, but zinc won’t.

Chemical and physical properties – So what?
Sulfur smells awful. Rotten eggs, onions, and garlic all have sulfur in them. Stink bombs use sulfur to create a bad smell. Sulfur is also flammable, and it is one of the 3 main ingredients in gun powder.

Chemical and physical properties – So what?
Chromium is famous for its intense luster. Chrome plated tools, jewlery, silverware, or car parts are very popular.

Chemical and physical properties – So what?
Most bullets are made of lead because lead is a very dense metal. These bullets are required, by international law, to be coated with a different metal because lead has such a low melting point and is so malleable.

Chemical and physical properties – So what?
The most dense elements are Iridium and osmium which have a density of about 22.6 g/cm3

Physical Change A Physical change is a change in a substance that does not change what the substance is.

Physical Change - examples
Examples of physical change include: Change in shape Change in size Change in phase Melting (solid to liquid) Boiling (liquid to gas) Evaporation (liquid to gas) Condensation (gas to liquid) Freezing (liquid to solid) Sublimation (solid to gas) Deposition (gas to solid)

Physical Change Physical changes might be caused by: Grinding Cutting
Crushing Bending Breaking Heating/cooling (change in phase) squishing

Physical Change Evidence that a physical change has occurred might include: Change in shape Change in form Change in size Change in phase (This is always a physical change!) Physical changes are usually reversible

Chemical change A chemical change is a change in which a substance is changed into a different substance. (You’ve changed what it is.)

Chemical change Examples of chemical changes include: Burning Rusting
Tarnishing Decomposing Polymerization

Chemical change Chemical changes occur when a chemical reaction causes bonds between atoms to break or to form.

Chemical change – Chemical reactions
There are 5 types of chemical reactions that cause chemical changes to occur.

Chemical change – Chemical reactions
1- Composition reactions Two things come together to form something new A + B = AB 2H2 + O2  2H2O

Chemical change – Chemical reactions
2- Decomposition reactions 1 thing breaks apart to form 2 or more things. AB = A + B 2H2O  2H2 + O2

Chemical change – Chemical reactions
3- Single replacement reactions One atom replaces another atom A + BC = AC + B or A + BC = AB + C Mg + 2HCl  H2 + MgCl2

Chemical change – Chemical reactions
Double replacement reactions Two chemicals switch places AX + BY = AY + BX 2KI + Pb(NO3)2  PbI2 + 2KNO3

Chemical change – Chemical reactions
Combustion reaction A substance combines with oxygen and releases energy. C3H8 (propane) + 5O2  3CO2 + 4H2O

Chemical Change: Evidence
Evidence that a chemical change has occurred might include: A color change An odor change Formation of a precipitate (you mix two liquids and make a solid) Gas is formed (bubbles) Changes in physical properties.

Physical and Chemical change
During a chemical change energy can be released in the form of: Heat Light

Physical and Chemical change - heat
A chemical reaction that releases energy in the form of heat is called exothermic. Heat comes OUT Exo = out Thermic = heat It will feel HOT.

Physical and Chemical change - heat
A chemical reaction that absorbs energy in the form of heat is called endothermic. Heat goes IN Endo = in Thermic = heat It will feel COLD

I. Law of Conservation of Mass
Although chemical changes occur, mass is neither created nor destroyed in a chemical reaction Mass of reactants equals mass of products massreactants = massproducts A + B  C

I. Conservation of Mass GIVEN: WORK: 10.00 g = 9.86 g + moxygen
In an experiment, g of red mercury (II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of the oxygen formed in the reaction? GIVEN: Mercury (II) oxide  mercury + oxygen Mmercury(II) oxide = g Mmercury = 9.86 g Moxygen = ? WORK: 10.00 g = 9.86 g + moxygen Moxygen = (10.00 g – 9.86 g) Moxygen = 0.74 g Mercury (II) oxide  mercury + oxygen Mmercury(II) oxide = g Mmercury = 9.26 Moxygen = ? massreactants = massproducts