Year EndExamReviewDay1, 2013.pdf

Year End

Exam Review

Day 1

Calculating Percent Error

Accepted Value – Experimental Value X 100 = Percent Error Accepted Value

 Percent Error is an absolute value (never a negative number)

Significant Figures

Use with

Measurements!

1. Leading 0’s NEVER count

2. Trailing 0’s count ONLY if there is a decimal 3. Trapped 0’s ALWAYS

count

 Do not use SFs with FACTS!

Scientific Notation

• With Scientific Notation, you always have one, and only one, digit to the left of the decimal place • When written in scientific notation, numbers

greater than 10 have positive exponents

• Numbers between 1 and 10 are not written in scientific notation

• When written in scientific notation, numbers less than 1 have negative exponents

Multiplication

To multiply numbers written in SN, multiply the coefficients and add the exponents

Division

To divide, divide the coefficients, and subtract the exponent in the denominator from the exponent on the numerator

Addition and Subtraction Before you can add or subtract SNs, you must

make the exponents the same. It does not matter which exponent you change.

Periodic Table

Know the names =

symbols of the 1

36 elements!

Plus other common

ones: Hg, Au, Ag,

Pb, Xe, Rn, Sn

Balancing Equations:

Law of Conservation of Matter

equations—they reflect the relative number of units of each substance involved in the reaction

Subscripts indicate the number of atoms present in a compound

Rules for Balancing Equations

and products

Put the reactants on the left side of the yields sign (→) put the products on the right

C

H

OH + O

→ CO

+ H

O

C

H

OH + O

→ CO

+ H

O

1) Set the equation up algebraically:

2) Do an atom inventory:

a

C

H

OH +

b

O

→

c

CO

+

d

H

O

C: 2

a

=

c

H: 6

a

= 2

d

O: 1

a

+ 2

b

= 2

c

+ 1

d

3) Make one coefficient = 1; solve for

the other coefficients:

a

= 1

C: 2(

a

) =

c

, 2(1) =

c

,

2 =

c

H: 6(

a

) = 2(

d

), 6(1) = 2

d

, 6 = 2

d

,

3 = d

O:

1

a

+ 2

b

= 2

c

+ 1

d

, 1(1) + 2

b

= 2(2) + 1(3)

Solve for b: 1 + 2

b

= 7, 2

b

= 6,

b = 3

a

C

H

OH +

b

O

→

c

CO

+

d

H

O

C

H

OH +

3

O

→

2

CO

+

3

H

O

Zn: a(1) = c(1) → a = c

H: b(1) = d(2) → b = 2d

Cl: b(1) = c (2) → b = 2c

3) Make one coefficient = 1; solve for the other coefficients

a = 1. Since a = c, c = 1. b = 2c --- b = 2 (1) --- b = 2

4) Do another atom inventory

C

H

OH +

3

O

→

2

CO

+

3

H

O

C: 2 → 2

H: 6 → 6

0: 7 → 7

Equation is balanced!

You are watching a soccer game. The Cougars are winning! There is 0.20 of an hour left in the game. How many seconds are left?

• Start with the knowns…

• What are you solving for?

• Plan a solution using Conversion Factors

• Make sure your units cancel out!

• Do the calculations

Dimensional Analysis

3, 1, 12, 7, 19

Mean?

Median?

Range?

SI Units

Quantity Unit Abbreviation Mass kilogram kg Length meter m Time second s Temperature Kelvin K Amount of Substance mole mol Electrical Current ampere A

Metric Prefixes

Prefix Abbreviation Meaning Example mega- M 106 _{1 megabyte = 1,000,000 bytes}

kilo- k 103 _{1 kilogram = 1,000 g}

deci- d 10-1 _{1 deciliter = 0.1 liter}

centi- c 10-2 _{1 centimeter = 0.01 meter}

milli- m 10-3 _{1 milliampere = 0.001 A}

micro- u 10-6 _{1 micrometer = 10}-6 _m

Know numerical prefixes

1 = mono-

6 = hexa-

2 = di-

7 = hepta

3= tri-

8 = octo-

4 = tetra-

9 = nona-

5 = penta-

10 = deca-

Percent Recovery

Final volume x 100 = % Recovery

Initial Volume

Do not confuse with percent loss!

Histogram

•

Matter: anything

that occupies space

and has mass

•

Density: Mass ÷

ATOMS!

particle possessing the properties of an element)

Elements are composed of only one type of atom

Electrical Nature of Matter

•

Protons +

•

Electrons -

•

Neutrons (no charge)

Ions and Ionic Compounds Atoms gain/lose electrons to become ions

• Electrically charged

• atoms or groups of atoms

–Cation

–Anion

Polyatomic Ions:

Sodium Ion: 11 protons (11 + _charge) + 10 electrons (10 – _charge) Sodium ion ( 1 + _{charge) Na}+

Naming Rules:

1) Name Cation 1

_{, then Anion}

next -- Na

_Cl

_NaCl

2) Suffix of anion ends in (-ide)

2) Correct Formula has fewest

positive and negative ions

needed to make the electrical

charge neutral

C.12: Gases and Temperature?

“Like dissolves like”

• Water will dissolve other polar substances • Will dissolve sugar and ethanol, which are polar

substances

• Oil and Water?

•Oil is non-polar, so it does not readily dissolve in water

Percent Concentration

Solute x 100 = Percent Concentration

Solution

• Physical Properties: color, odor, density---can be determined without altering the make-up of the substance

• Chemical Properties: relate to the chemical changes that the substances undergo: when atoms are rearranged

Periodic Table

 Where are the Periods? The Groups/Families?  Metals/Non-Metals

 Alkali Metals  Alkaline Earth Metals  Transition Elements  Metalloids

 Halogens  Noble Gases

A compound must be

electrically neutral!

If you have Na

_{+ SO}

42-

, you

would have NaSO

To make it electrically neutral, you

must have 2 sodiums! Na

SO

Atomic Number vs.

Mass Number vs. Atomic Mass

Atomic Number

•Always the number of protons the element has •Uniquely identifies the element

•Always a whole number Mass Number

Mass Number

• Number of Protons and Neutrons (found in nucleus)…always a whole number

Atomic Mass (AMU for a single atom---grams for a mole) • Mass of protons, electrons, and neutrons

• Not a whole number…why?

Isotopes are different types of atoms of the same element that have a different number of neutrons

Activity Series

Some Metals

are more

reactive than

others

Redox Reactions

2AgNO_3(aq) + Cu _(s) Cu(NO₃)_2(aq) + 2Ag_(s)

2 events

1)

Reduction :

gain electrons

2)

Oxidation :

lose electrons

LEO the lion says GER!

L

osing

E

lectrons =

O

xidation

G

aining

E

lectrons =

R

eduction

Oxidation or Reduction Reaction?

What is the Reducing Agent?

Li Li

₊

_e

2I I

_{+ 2}

_e

Zn

_{+ 2}

_e

_Zn

Three key points!

a loss of electrons

2) The reactant that produces electrons is the reducing agent – it gets oxidized.

2) There can be no oxidation without reduction and visa versa !

Evidence of a Chemical Reaction

oTemperature Change oGas Release oDisintegration, or

formation of a new substance oOdor