Physical Science EOCT Review

Domain 2: Chemistry-Chemical Reactions and

Properties of Matter

Domain 2: Chemistry- Matter

Matter• Matter is anything that: a) has

mass, and b) takes up space

• Mass = a measure of the amount

of “stuff” (or material) the object

contains (don’t confuse this with

weight, a measure of gravity)

• Volume = a measure of the space

occupied by the object

Properties are…• Words that describe matter (adjectives)

• Physical Properties- a property that can be observed and measured without changing the material’s composition.

• Examples- color, hardness, m.p., b.p.

• Chemical Properties- a property that can only be observed by changing the composition of the material.

• Examples- ability to burn, decompose, ferment, react with, etc.

States of matter1) Solid- matter that can not flow (definite

shape) and has definite volume.

2) Liquid- definite volume but takes the shape of its container (flows).

3) Gas- a substance without definite volume or shape and can flow.

– Vapor- a substance that is currently a gas,

but normally is a liquid or solid at room

temperature. (Which is correct: water gas,

or water vapor?)

States of MatterStates of Matter

Solid

Liquid

Gas

Definite Volume?

YES

YES

NO

Definite Shape?

YES

NO

NO

Result of a

TemperatureIncrease?

Small

Expans.

Small

Expans.

Large

Expans.

Will it Compress?

NO

NO

YES

4th state: Plasma - formed at

high temperatures; ionized phase of matter as found in the sun

Solid Liquid Gas

Melt Evaporate

CondenseFreeze

Physical vs. Chemical Change• Physical change will change the

appearance, without changing the

composition of the material.

– Boil, melt, cut, bend, split, crack

– Is boiled water still water?

• Can be reversible, or irreversible

• Chemical change - a change where a

new form of matter is formed.

– Rust, burn, decompose, ferment

• Mixtures are a physical blend of at least two substances; have variable composition. They can be either:

1) Heterogeneous – the mixture is not uniform in composition

• Chocolate chip cookie, gravel, soil.

2) Homogeneous - same composition throughout; called “solutions”

• Kool-aid, air, salt water

• Every part keeps it’s own properties.

Separating Mixtures

• Some can be separated easily by

physical means: rocks and marbles, iron filings and sulfur (use magnet)

• Differences in physical properties

can be used to separate mixtures.

• Filtration - separates a solid from the liquid in a heterogeneous mixture (by size) – Figure 2.7, page 46

Substances• Elements- simplest kind of matter

– cannot be broken down any simpler

– all one kind of atom.

• Compounds are substances that can be broken down only by chemical methods– when broken down, the pieces have

completely different properties than the original compound.

– made of two or more atoms, chemically combined (not just a physical blend!)

Compound or Mixture?

Compound Mixture

Made of one kindof material

Made of more thanone kind of material

Made by a chemical change

Made by a physical change

Definitecomposition

Variablecomposition

Which is it?

ElementCompoundMixture

Elements vs. Compounds

• Compounds can be broken down

into simpler substances by chemical means, but elements

cannot.

• A “chemical change” is a change that produces matter with a different composition than the original matter.

Classification of Matter

Domain 2: Chemistry-Chemical Reactions

Naming cations

• Two methods can clarify when

more than one charge is possible:

1) Stock system – uses roman

numerals in parenthesis to indicate the numerical value

Naming cations• We will use the Stock system.

• Cation - if the charge is always the same (like in the Group A metals) just write the name of the metal.

• Transition metals can have more than one type of charge.

• Indicate their charge with roman numerals in parenthesis after the name of the metal

Naming Anions

• Anions are always the same charge

• Change the monatomic element ending to – ide

• F1- a Fluorine atom becomes a Fluoride ion.

Polyatomic ions are…• Groups of atoms that stay together and

have an overall charge, and one name.

• Usually end in –ate or -ite

• Acetate: C2H3O21-

• Nitrate: NO31-

• Nitrite: NO21-

• Permanganate: MnO41-

• Hydroxide: OH1- and Cyanide: CN1-?

Writing Ionic Compound Formulas

Example: Barium nitrate

1. Write the formulas for the cation and anion, including CHARGES!

BaBa2+2+ NONO33--

2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross

method to balance subscripts.

Not balanced!

( )( )22

Now balanced.

= Ba(NO3)2

Writing Ionic Compound Formulas

Example: Iron (III) chloride

1. Write the formulas for the cation and anion, including CHARGES!

FeFe3+3+ ClCl--

2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross

method to balance the subscripts.

Not balanced!

33Now balanced.

= FeCl3

Writing Ionic Compound Formulas

Example: Magnesium carbonate

1. Write the formulas for the cation and anion, including CHARGES!

MgMg2+2+ COCO3322--

2. Check to see if charges are balanced.

They are balanced!

= MgCO3

Naming Ionic CompoundsNaming Ionic Compounds• 1. Name the cation first, then anion

• 2. Monatomic cation = name of the

element

Ca2+ = calcium ion

• 3. Monatomic anion = root + -ide

Cl− = chloride

CaCl2 = calcium chloride

Naming Ionic CompoundsNaming Ionic Compounds

• some metals can form more than one

charge (usually the transition metals)

• use a Roman numeral in their name:

PbCl2 – use the anion to find the charge on the cation (chloride is always 1-)

Pb2+ is the lead (II) cation

PbCl2 = lead (II) chloride

(Metals with multiple oxidation states)(Metals with multiple oxidation states)

Things to look for

• If cations have (_), the number

in parenthesis is their charge.

• If anions end in -ide they are

probably off the periodic table

(Monoatomic)

• If anion ends in -ate or –ite,

then it is polyatomic

Molecular compounds are…

• made of just nonmetals

• smallest piece is a molecule

• can’t be held together

because of opposite charges.

• can’t use charges to figure out how many of each atom

Molecular compounds are easier!• Ionic compounds use charges to

determine how many of each.

–Have to figure out charges.

–May need to criss-cross numbers.

• Molecular compounds: the name

tells you the number of atoms.

• Uses prefixes to tell you the exact

number of each element present!

Prefixes (Table 9.4, p.269)• 1 = mono-

• 2 = di-

• 3 = tri-

• 4 = tetra-

• 5 = penta-

• 6 = hexa-

• 7 = hepta-

• 8 = octa-

Prefixes

• 9 = nona-

• 10 = deca-

• To write the name, write two words:

• One exception is we don’t write mono- if there is only one of the first element.

• Normally do not have double vowels when writing names (oa oo)

Prefix name Prefix name -ide

Practice by naming these:

• N2O

• MgCO3

• Cl2O7

• TiS

• CO2

• BaCl2

Write formulas for these:• diphosphorus pentoxide

• tetraiodine nonoxide

• Iron (III) oxide

• nitrogen trioxide

• Calcium sulfide

• Potassium iodide

• aluminum chloride

Chemical Reactions are…• When one or more substances are

changed into new substances.

• Reactants- the stuff you start with

• Products- what you make

• The products will have NEW

PROPERTIES different from the

reactants you started with

• Arrow points from the reactants to the

new products

Recognizing Chemical Changes

1) Energy is absorbed or released

(temperature changes hotter or colder)

2) Color changes

3) Gas production (bubbling, fizzing, or odor

change; smoke)

4) formation of a precipitate - a solid that

separates from solution (won’t dissolve)

5) Irreversibility - not easily reversed

But, there are examples of these that are not

chemical – boiling water bubbles, etc.

Conservation of Mass • During any chemical reaction, the

mass of the products is always equal

to the mass of the reactants.

• All the mass can be accounted for:

– Burning of wood results in products that appear to have less mass as ashes; where is the rest?

• Law of conservation of mass

4. Balanced Chemical Equations

• Atoms can’t be created or destroyed in an ordinary reaction:

–All the atoms we start with we must end up with

• A balanced equation has the

same number of each element on

both sides of the equation.

Rules for balancing:1) Assemble the correct formulas for all the

reactants and products, use + and →

2) Count the number of atoms of each type appearing on both sides

3) Balance the elements one at a time by adding coefficients where needed (the numbers in front) - save balancing the H and O until LAST!

(I prefer to save O until the very last)

4) Check to make sure it is balanced.

• Never change a subscript to balance an equation.

– If you change the formula you are describing a different reaction.

– H2O is a different compound than H2O2

• Never put a coefficient in the middle of a formula

2NaCl is okay, but Na2Cl is not.

Types of Chemical Reactions

• Combination A+B � AB

• Decoposition AB� A + B

• Single Replacement AB + C � AC + B

or A + BC � AC + B

• Double Replacement AB + CD � AD + CB

• Combustion CH(O) + O2 � CO2 + H20

• If O2 limited CH(O) + O2 � CO + H20

• If O2 limited CH(O) + O2 � C + H20

#1 - Combination Reactions• Combine = put together

• 2 substances combine to make one compound.

• Ca +O2 → → → → CaO

• SO3 + H2O →→→→ H2SO4

• We can predict the products if the reactants are two elements.

• Mg + N2 → ____→ ____→ ____→ ____

#2 - Decomposition Reactions• decompose = fall apart

• one reactant breaks apart into two or more elements or compounds.

• NaCl Na + Cl2• CaCO3 CaO + CO2

• Note that energy (heat, sunlight,

electricity, etc.) is usually required

electricity →→→→

∆∆∆∆ →→→→

#3 - Single Replacement

• One element replaces another

• Reactants must be an element and a compound.

• Products will be a different element and a different compound.

• Na + KCl →→→→ K + NaCl

• F2 + LiCl →→→→ LiF + Cl2

#4 - Double Replacement• Two things replace each other.

– Reactants must be two ionic compounds.

– Usually in aqueous solution

• NaOH + FeCl3 →

– The positive ions change place.

• NaOH + FeCl3 → Fe+3 OH- + Na+1 Cl-1

• NaOH + FeCl3 → Fe(OH)3 + NaCl

#5 - Combustion• Means “add oxygen”

• Normally, a compound composed of only C, H, (and maybe O) is reacted with oxygen – usually called “burning”

• If the combustion is complete, the products will be CO2 and H2O.

• If the combustion is incomplete, the products will be CO (or possibly just C) and H2O.

Domain 2: Chemistry-Properties of Matter

Solvents and Solutes• Solution - a homogenous mixture, that

is mixed molecule by molecule.

• Solvent - the dissolving medium

• Solute -the dissolved particles

• Aqueous solution- a solution with water

as the solvent.

• Particle size less than 1 nm; cannot be

separated by filtration – Fig. 15.6, p.450

1. SoluteA solute is the dissolved substance in a

solution.

A solvent is the dissolving medium in a

solution.

2. Solvent

Salt in salt water Sugar in soda drinks

Carbon dioxide in soda drinks

Water in salt water Water in soda

Parts of a Solution:

Dissolution of Solid SoluteWhat are the driving forces which cause solutes to dissolve to form solutions?

1. CovalentCovalent solutes dissolve by H-bonding to water

2. Ionic solutes dissolve by dissociation into

their ions.

These ions have

been surrounded

by water, and are

now dissolved!

• Solids will dissolve if the attractive force of the water molecules is stronger than the attractive force of the crystal.

• If not, the solids are insoluble.

• Water doesn’t dissolve nonpolarmolecules (like oil) because the water molecules can’t hold onto them.

• The water molecules hold onto other water molecules, and separate from the nonpolar molecules.

• Nonpolars? No repulsion between them

Electrolytes and Nonelectrolytes

• Electrolytes- compounds that conduct

an electric current in aqueous solution,

or in the molten state

– all ionic compounds are electrolytes because they dissociate into ions (they are also called “salts”)

• barium sulfate- will conduct when

molten, but is insoluble in water!

Electrolytes and Nonelectrolytes• Do not conduct? = Nonelectrolytes.

– Most are molecular materials, because they do not have ions

• Not all electrolytes conduct to the

same degree

– there are weak electrolytes, and strong electrolytes

– depends on: degree of ionization

Solution formation

• The “nature” (polarity or composition) of the solute and the solvent will determine…

1. Whether a substance will dissolve

2. How much will dissolve

• Factors determining rate of solution...

1. stirring (agitation)

2. surface area the dissolving particles

3. temperature

Making solutions• In order to dissolve, the solvent

molecules must come in contact

with the solute.

1. Stirring moves fresh solvent into

contact with the solute.

2. Smaller pieces increase the amount

of surface area of the solute.

- think of how fast a breath mint

dissolves when you chew it

Temperature and Solutions

3. Higher temperature makes the

molecules of the solvent move around faster and contact the solute harder and more often.

– Speeds up dissolving.

• Higher Temperature Also Usually

increases the amount that will dissolve (an exception is gases)

Domain 2: Chemistry- Acids and Bases

Properties of acids

• Taste sour (don’t try this at home).

• Conduct electricity.

–Can be strong or weak electrolytes in

aqueous solution

• React with metals to form H2 gas.

• Change the color of indicators (blue litmus to red).

• React with bases (hydroxides) to form

water and a salt.

Acids Affect Indicators

Blue litmus paper turns red in contact with an acid.

Acids have a pH less than 7

Acids Neutralize Bases

HCl + NaOH → NaCl + H2O

-Neutralization reactions ALWAYS produce a salt and water.

-Of course, it takes the right proportion of acid and base to produce a neutral salt

Properties of bases• React with acids to form water

and a salt.

• Taste bitter.

• Feel slippery (don’t try this either).

• Can be strong or weak electrolytes in aqueous solution

• Change the color of indicators (red litmus turns blue).

Bases Affect Indicators

Red litmus paper

turns blue in contact

with a base.Phenolphthalein

turns purple in a

base.

Bases

have a

pH

greater

than 7

Bases Neutralize Acids

Milk of Magnesia contains

magnesium hydroxide,

Mg(OH)2, which neutralizes

stomach acid, HCl.

2 HCl + Mg(OH)2

MgCl2 + 2 H2O