Ultimate Science Review

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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ULTIMATE SCIENCE REVIEW 436 AND 416 BY: JOSEPH SZYMBORSKI

TOPICS: • • • • • • • • • • • • • • • • • • • • •

Dimensional Analysis Scientific Notation Properties Physical and Chemical Change Elements and Compounds Mixtures (Heterogeneous & Homogeneous) Philosophers and Scientists Electrostatics Protons, Neutrons and Electrons Bohr-Rutherford Diagrams Cathode Ray Tube Radioactivity Copper Oxide Labs Percent Yield Names of the Elements (1-36) Isotopes Average Atomic Mass Chemical Reactivity Periodic Trends Metals, Non-Metals and Metalloids Four Families

• • • • • • • • • • • • • • • • • • • • • •

Molecules Balancing Equations Mole Stoichiometry Structures of Matter Nomenclature Magnetism Electromagnetism Conductors/Insulators Theory on I/V/R Resistors Ohm's Law Req Series/Parallel/Combo Kirchoff Series/Parallel Power Equations Read a Hydrometer Heat Heat -> Electrical power Concentration / Solutions / Dilutions Acids, bases and salts Indicators pH

DIMENSIONAL ANALYSIS: • • •

Dimensional Analysis can always (and should always) be solved in one line The focus is put on units (dimensions) You should start with a certain unit, and end by canceling out units via conversion factors to end with the result that is asked of you

EX: The density of air is 0.00129 g/ml. What volume (in liters) will 1g of air occupy? 1ml 1g x ------x 0.00129g

1cl -------10ml

1dl 1L x -------- x ------- = 0.775193798 L 10cl 10dl

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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SCIENTIFIC NOTATION: •

Scientific Notation involves bringing a digit to only one number before the decimal and adding it by powers of 10 to equate it.

EX: 432.987 = 4.32987 x 102

0.00000567 = 5.67 x 10-6

PROPERTIES: • • •

There are two types properties: Characteristic and Non-Characteristic Characteristic properties are unique to only one substance Non-characteristic properties are shared between multiple substances EX: Property

PHYSICAL AND CHEMICAL Has a melting point of -77.7oC CHANGES: Is colorless • There are two type of changes: physical and chemical changes • Chemical changes are permanent. • Physical changes can be reversed.

C OR NC C NC

Has a density of 0.76 g/L

C

Reacts with HCl (g) to produce a white smoke

C

In solution, turns red litmus paper blue

C

Has a temperature of -26.3oC

NC

Has a mass of 2 g

NC

Has a boiling point of -33.5 C o

C

ELEMENTS AND COMPOUNDS: • •

Elements are substances in their pure state such as that found on the periodic table of elements Compounds are constituted of two or more elements which have one to three bonds with one another

EX: Copper (or Cu), Iron (or Fe) and Neon (Ne) are elements whereas Salt (NaCl), Ammonia (NHO3) and Carbon Dioxide (CO2)

MIXTURES (HETEROGENOUS AND HOMOGENOUS): • •

Homogeneous mixtures are substance which are equally distributed within another one Heterogeneous mixtures are unevenly distributed within another one

EX: Oil and Water is Heterogeneous while A Conductive solution is Homogeneous (Read:

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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Electrolytes)

PHILOSOPHERS AND SCIENTISTS: Aristotle maintained that matter does not contain atoms and that anything can be infinity divided (Continuous Theory) • Democritus maintained that matter is made of atoms (Discontinuous Theory) and all things are made of the same atoms in a different arrangement (the latter being incorrect) • Dalton believed in four main rules: 1) All mater is composed of tiny indivisible atoms 2) All atoms of the same element are the same 3) Atoms of different elements are different 4) During a chemical reaction, atoms combine and form bonds to create new atoms • J.J Thompson maintained three main beliefs: 1) Protons are positively charged 2) Electrons are negatively charged 3) Atoms are neutrally charged because they have the same amount of protons as they do electrons • Created the plum pudding model (which is incorrect) • Rutherford held the belief that: 1) The atom is made mostly of space 2) The Nucleus is mostly positive 3) The nucleus is very dense 4) The number of protons and neutrons vary from element to element • Created the Rutherford model which involved electrons revolving around the nucleus in no particular order • Niels Bohr added to Rutherford's model by introducing electron orbits and shells •

ELECTROSTATICS: • •

Ex:

All matter is neutral Some attract a stronger negative charge than others (Silk, Wool, Cotton, Rubber)

More Negative ==== Likely to Receive

Rubber Ebonite Polyethylene Cotton Silk Wool Glass Acetate

More Positive ==== Likely to Give Away

PROTONS, NEUTRONS AND ELECTRONS: Protons 1u Positively Charged Inside the Nucleus

Neutrons 1u Negatively Charged Inside the Nucleus

Electrons 0u (1/1837 u) Negatively Charged Outside the Nucleus

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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BOHR-RUTHERFORD DIAGRAMS: •

Energy shells only can hold a certain amount of electrons. Their capacities are as follows: • Level 1 = 2 Particle Calculations • Level 2 = 8 • Level 3 = 8 Protons ( p+ ) = ATOMIC NUMBER • Level 4 = 18 Electrons ( e- ) = ATOMIC NUMBER • Level 5 = 32 Neutron ( n0 ) = ATOMIC MASS-ATOMIC NUMBER • Level 6 = 50

EX: p+ 3 n0 7 2e-

1e-

CATHODE RAY TUBE:

• • • • • • •

Cathode ray tube is made up of a vacuum tube. Inside said tube are two electrodes, an anode (+) and a cathode (-) Energy flows from cathode to anode Heater heats up so much it releases electrons Electrons bump into argon gas in vacuum and create a greenish ray Deflection plates make sure it flows in a beam An electron beam is made of electron particles (negative charge)

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RADIOACTIVITY: • • •

Everything Dies ( After you get over the sadness, note that so do elements.) Unstable atoms undergo decay Decay means particles from the atom will fly off into it's surroundings Name

Symbol

Charge

Penetrating Range

Alpha Particles

α

+

Less

Beta Particles

β

-

More

Gamma Particles

γ

o

Most

COPPER OXIDE LAB: • •

When you burn something, you often introduce oxygen to it When you burn copper you introduce O2 (Oxygen) to it

EX: Cu + O2 = 2 CuO2

PERCENT YIELD: •

Percent yield is equal to: FINAL MASS -----------------------------THEORETICAL YIELD

• • •

Final Mass is given or calculated by subtracting crucible or weighing paper mass Theoretical yield is equal to: INITIAL MASS ---------------------------- X ATOMIC MASS OF COMPOUND ATOMIC MASS

NAMES OF THE ELEMENTS (1-36): 1 Hydrogen H 2 Helium He 3 Lithium Li 4 Beryllium Be 5 Boron B

6 Carbon C 7 Nitrogen N 8 Oxygen O 9 Fluorine F 10 Neon Ne

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI 11 Sodium Na 12 MagnesiumMg 13 Aluminum Al 14 Silicon Si 15 PhosphorusP 16 Sulfur S 17 Chlorine Cl 18 Argon Ar 19 Potassium K 20 Calcium Ca 21 Scandium Sc 22 Titanium Ti 23 Vanadium V 24 Chromium Cr 25 Manganese Mn 26 Iron Fe

6/25 27 Cobalt Co 28 Nickel Ni 29 Copper Cu 30 Zinc Zn 31 Gallium Ga 32 GermaniumGe 33 Arsenic As 34 Selenium Se 35 Bromine Br 36 Krypton Kr 51 Antimony Sb 52 Tellurium Te 83 Bismuth Bi 84 Polonium Po * Bold elements denote a metalloid

ISOTOPES: •

•

•

Two types of Isotopes: ◦ Natural ◦ Artificial Natural Isotopes ◦ Found in environment ◦ Most are stable but some are unstable (radioisotopes) ◦ Unstable are radioactive ◦ Some formed during formation of the earth ◦ Some by bombardment of cosmic rays in the atmosphere ◦ EX: Uranium, thorium, radon gas Artificial Isotopes ◦ Artificial isotopes are created inside nuclear reactors ◦ Bombardment of atoms with other atomic particles

AVERAGE ATOMIC MASS: • •

Atomic masses of atoms don't increase regularly This is b/c neutrons don't increase regularly

EX: Lithium (Li): 3 Protons , 4 Neutrons Total: 7 Nucleons So is called Lithium-7 or Li-7

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92.58% of all lithium isotopes that exist are Li-7 7.42% of lithium isotopes are Li-6 Li-6 : 3 Protons, 3 Protons Total: 6 Nucleons So it is called Li-6 • • •

These percentages are called Relative Abundances Atomic Mass is not an integer because it is a weighted average Atoms of the same element have the same # of protons but neutrons vary AVERAGE ATOMIC MASS = (MASS NUMBER ISTOPE 1 X % ABUNDANCE 1) + (MASS NUMBER ISTOPE 2 X % ABUNDANCE 2) + (MASS NUMBER ISTOPE 3 X % ABUNDANCE 3) ETC...

EX: The percent abundance for the isotope of potassium with the least amount of neutron is 94%, while the percent abundance of the isotopes with the second-least amount of neutrons is 5%. Calculate the average atomic mass of potassium. 39.10 = (x-1 x 0.05) + (x-2 x 0.94) + (x-3 x 0.01)

39.10 = 0.05 x – 0.05 + 0.94 x – 1.88 + 0.01 x 39.10 = -1.93 + x 41.03 = x (39 x 0.94) + (40 x 0.05) + (41 x 0.01) = 39.07u

CHEMICAL REACTIVITY: • • • •

Reactivity is determined by valence shell Families have same valence, ergo the same reactivity Group number = valence For metals, reactivity increases from right to left in a period and top from bottom in a family

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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For non-metals, reactivity increase left to right in a period and bottom to top in a family

•

In chemical reactions, atoms tend to become as stable as possible. They try to acquire the electron configuration of the closest inert gas in the period by either losing or gaining electrons

EX: Li + F → LiF 3 Na + N → Na3N Mg + 2 Cl → MgCl2 Ca + 2 Br → CaBr2 Ra + At → Ra2At

PERIODIC TRENDS: • • •

Certain trends can be observed in the periodic table concerning the atomic properties Atomic Mass: The mass in mol/g for each element increases from left to right Why? From left to right, up to down, the atomic number increases. This means that the protons increase and protons make up the majority of the mass of the atom.

•

Metallic Properties: Metallic properties like conductors of both electricity and heat. This increases right to left Why? Metals are on the right side of the table

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Atomic Radius: Atomic radius (the proximity of the electron shells to the nucleus) increases right to left Why? The less positive the nucleus is, the further away the electron shell is, the larger the atomic radius number is. The nucleus becomes more positive the higher the atomic number gets (from left to right)

Ionization Energy: Energy required to remove 1 mol of electrons from material composed in a single atom (measured in kJ/mol) increases from right to left Why? Right side (other than inert gases) already want to give away their electrons

Electronegativity: Ability of an atom to attract electrons to itself. More or less opposite of Ionization Energy. Measured on the Paulis Scales, a dimensionless scale from 0.7 to 4 (like Richter scale). Why? Left side already wants to receive electrons

Characteristic Properties: Density (g/ml), Boiling Point (ºc or K), Melting Point (ºc or K) etc are all greater in the middle of the table.

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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METALS, NON-METALS AND METALLOIDS:

•

•

•

Metals are characteristically electrically and thermally conductive, usually solids at room temperature, are generally malleable, ductile and lustrous and are found typically from the 1st to 13th family Metalloids have some of the same characteristic properties as metals and some properties from the non-metals. They are found along the step-line which is located between the metals and the nonmetals Non-Metals are characteristically not lustrous, usually gases at room temperature, not malleable, ductile or good conductors of electricity and heat. They are found increasingly from the 14th to 18th family.

FOUR FAMILIES: •

Alkali Metals (IA), when in presence of water create a base and hydrogen gas EX: 2 Li(g) + H2O(l) → 2 LiOH(l) + H2(g)

•

Alkaline Earth Metals (IIA), much like Alkali metals, create a base and hydrogen gas when in presence of water EX: Ca + 2 H2O → H2(g) + Ca(OH2)(g)

•

Halogens (VIIA), halogens have a high electronegativity and often have colors attributed to them

•

Inert Gases (VIIIA), Inert gases (a.k.a Noble Gases) have a full valence shell and tend not to bond with other elements. These are, as the family name suggests, gases at room temperature and are normally colorless unless electrically charged.

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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MOLECULES: • • • •

Molecules are two or more ionicaly or covalently bonded atoms Each atom has a valence (not valence electron) A valence is the number of bonds that an atom of an element can form The octet rule states that an atom with eight electrons in it's outer energy level is chemically stable and unstable Rules of Valence 1. The valence of an element in family 1, 2, or 3 is the same as the family or group number 2. The valence of an element in family 4, 5, 6 or 7 is equal to 8 minus the family number (Inert gases do not have a valence value)

EX: Since H can form 1 bond (valence 1) and O can form 2 bonds (valence 2) then O can combine 2 H atoms to form water

•

Bonds There are two types of chemical bonds (for our purposes): ◦ ionic (exchange electrons) ◦ covalent (sharing electrons) ◦ James (license to kill electrons)

Ionic Bonds • • •

Atoms that gain or lose electrons take on an electric charge and are called ions Bonds formed between ions are called ionic Ionic bonds usually only occur between metals and non-metals

11p+ 11e-------0 Na0

11p+ 10e-------1+ Na+1

17p+ 17e-------0 Cl0

17p+ 18e-------1Cl-1

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Covalent Bonds • •

Atoms that share pairs of electrons are said to form a covalent bond Covalent bond usually only occur between two identical non-metals and two metals

The Cross-Over Rule 1. Write the symbols of the two elements placing the metal first Mg

Br

2. Write the valence of each element as a superscript Mg2

Br1

Mg2

Br1

3. Cross over the valences 4. Divide the valences by the G.C.F (if necessary, in this case, it isn't) Mg1

Br2

5. Drop any subscript that is 1 MgBr2

BALANCING EQUATIONS: •

The most important concept to understand when balancing equations is tat the mass of the reactants is always equal to the mass of the products (Lavoisier's Law of Conservation of Mass)

EX: CH4 + 2 O2 → CO2 + 2 H2O Reactants

Products

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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Steps for balancing an equation 1. Pick the most complex reactant or product 2. Balance the elements contained in that substance on the other side of the equation 3. Continue until all substances are balanced 4. If there are any fractional coefficients, they must be eliminated by multiplaying every term by a constant

MOLE: 602,000,000,000,000,000,000,000 atoms in a mole (6.02 x 1023) • • •

The mole is the amount of substance that contains 6.02 x 1023 particles of that substance It can abbreviated as mol The number of moles of a given substance can be calculated with the formula MASS OF SUBSTANCE (g) m n= ----------------------------------------- = -------MOLAR MASS (g/mol) M

EX: 12g of Carbon is 1 mol or Carbon 44g of Carbon Dioxide is 1 mol of Carbon Dioxide 4g of Helium is 1 mol of Helium 40g of Argon is 1 mol of Argon 18g of water is 1 mol of water 40g of Calcium is 1 mol of Calcium

STOICHIOMETRY: • •

Are you stoic'd for stoichiometry? Stoichiometry is a method from which the quantities of substances required or produced from a given equation are defined.

EX: How many grams of Aluminum Bromide will you need to create the following reaction if you have 618.81 grams of Potassium Sulphate. 2 AlBr3 + 3 K2(SO4) → 6 KBr + Al2(SO4)

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

618.81gK2(SO4)

1 mol K2(SO4) 2 mol AlBr2 266.68 g AlBr2 X -----------X --------------- X ---------------206.67gK2(SO4) 3 mol K2(SO4) 1 mol AlBr2

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= 532.33 g

STRUCTURES OF MATTER: •

Three ways exist to illustrate the structure of matter: ◦ Lewis Dot ◦ Structural Formulas ◦ Dimensional Models

Lewis Dot • • EX:

Representation of the valence electrons by placing dots around the elements symbol Each family has a different configuration

Structural Formulas • • • EX:

In a structural formula, we can see the number and nature of the atoms, as well as their relative position within a molecule In a structural formula, the number of lines also represents the number of bonds formed between two atoms One line represents the sharing of one pair of electrons, two lines represents two bonds

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Dimensional Formulas • • • • • •

Matter can be represented in three-dimensional models All bonding rules governing structural formulas apply to dimensional models All single bonds are shown straight All double bonds and triple bonds are curved Bonds within a polyatomic molecule are shown slanted Balls shown in size relative to their nucleus

NOMENCLATURE: •

There are 3 rules for naming Binary Compounds. This depends on whether the compounds are ◦ Metal + Non-Metal ◦ Transition Metal + Non-Metal ◦ Non-Metal + Non-Metal

Metal + Non-Metal •

Name of metal + name of non-metal with -ide suffix

EX: NaCl = sodium chloride

CaO = calcium oxide MgF2 = magnesium floride Transition Metal + Non-Metal •

Name of Metal (with bond number in roman numerals) + name of non-metal with -ide suffix

EX: CuCl2 = copper (II) chloride AgBr = silver (I) bromide Fe2O3 = iron (III) oxide

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Non-Metal + Non Metal •

non-metal name with numeric prefix + non-metal name with numeric prefix

Numerical Prefixes: 1. 2. 3. 4. 5. 6.

Mono Di Tri Tetra Penta Plexa

EX: CO = carbon monoxide N2O3 = dinitrogen trioxide PCl3 = phosphorus trichloride H2O = dihydrogen monoxide (water)

Exception #1 H+ Ion + Halogen • EX:

Hydro + non-metal with -ic suffix + acid HCl = hydrochloric acid HF = hydrofloric acid

Exception #2 Polyatomic Compounds • EX:

Metal + Radical Ion LiOH = lithium hydroxide MgSO4 = magnesium sulphate CaCO3 = calcium carbonate

Radicals to know: - OH-1 - NO-1 -SO4-2 -PO4-3 -CO3-2 -NH4+1

hydroxide nitrate sulphate phosphate carbonate ammonium

Exception #3 Special Cases •

Some compounds were named so long ago that the rules do not apply to them:

EX: H2O water H2O2 peroxide CH4 ammonia

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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MAGNETISM: •

•

•

•

•

Forces in the Universe ◦ Gravity ◦ Weak Nuclear Forces ◦ Strong Nuclear Forces ◦ Magnetism (electromagnetism) 3 Categories of substances ◦ Magnetic ◦ Ferro-magnetic ◦ Non-magnetic Ferro-Magnetic Substances ◦ Any material which can become magnetic temporarily as long as they remain in the presence of a magnet Ferro-Magnetic Material ◦ Iron ◦ Cobalt

◦ Nickel Magnetic Substances

•

• • • •

◦ Any material which acts like a magnet (can be attracted and repelled by another magnet) ◦ Examples: lodestones, bar magnets Non-Magnetic ◦ Any material which is not attracted or repelled by a magnet. A magnet will not affect it. Every magnet has two poles: ◦ North and South Like poles repel, unlike poles attract As the distance between poles increase, the magnetic forces decrease. All magnets have a magnetic field ◦ Space around a magnet where magnetic forces are felt ◦ Lines of forces show you the shape,

direction and strength

ELECTROMAGNETISM: • •

•

A magnetic field created by the motion of electric charges (electrons) In other words, not only magnets can produce a magnetic field, current-bearing objects can also Straight Line Conductors Wires which have a current flowing through them, also have a magnetic field

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Solenoid Coiled wire which have a current flowing though them also have a magnetic field of a bar magnet Fingers wrap around the coil in the direction of the current flow and your thumb points in the direction of the magnetic field lines

CONDUCTORS/INSULATORS: Conductors •

Conductors are substances which easily allow electricity to flow through them

Insulators •

Insulators are substances which do not allow electricity to flow through them easily

Conductance •

Conductance is a number which tells you how well electricity flows through a

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI

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substance Conductors have a high conductance number (no duh) Unit of Conductance is Siemens (pronounced: see-mens-ha-ha-u-see-ree-us-that-espre-tee-fuh-nee) and the symbol is G Conductance of wire depends on: ◦ Type of material used ◦ Length of the wire ◦ Diameter of the wire (thickness of cross-sectional area) ◦ Temperature of the wire Property

Change

Result

Temperature

Increase

Decrease

Length

Increase

Decrease

Diameter

Increase

Decrease

THEORY ON I/V/R: Current Intensity • • •

Current intensity measures the amount of electrons which flows through an electric circuit in one second. It is often called “current” The symbol for current intensity is I The unit of current intensity is the ampere (A)

Potential Difference • Potential difference causes electrons to flow through a circuit • Potential difference is provided by either a battery or a power supply Resistance Conductance is how easily current flow though an object Resistance is how difficult it is for current to flow through an object The symbol for resistance is R The unit of resistance is Ohms 1 Resistance is the reciprocal of conductance or R = ----G • • • •

RESISTORS: •

Some resistors have a ceramic coating with color coded bands to indicate the resistance

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OHM'S LAW: •

Since voltage and current increases proportionally, there must be a constant to regulate the increase such that: V=I/R

EX:

9v

A

10Ω

I=?

9 = I x 10 9/10 = I = 0.9A

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Req OF SERIES/PARALLEL/COMBO:

Req Is the equivalent resistance of the circuit. When the circuit is in series, you simply add the resistance of all the resistance to get the Req EX: If R1 is 10Ω, R2 is 5Ω and R3 is 25Ω, what is the Req of the circuit on the left? 10Ω+5Ω+25Ω = 30Ω The Req of a parallel circuit is calculated as followed: 1 1 1 ---- = ---- + ---- .... Req R1 R2 EX: If R1 is 5Ω, R2 is 10Ω and R3 is 30Ω, what is the Req of the circuit on the left? 1 1 1 1 ----- ¨+ ----- + ------ = 0.34 = ----5Ω 10Ω 30Ω Req 1 Req= ----- = 3Ω 0.3333 Solving Series-parallel (combination or combo) circuits involves multiple steps. EX: If R1 is 20Ω, R2 is 10Ω and R3 is 30Ω, what is the Req of the circuit on the left? 1 1 1 ------ = ----- + ------ = 0.133 R2,3 10Ω 30Ω Req = 7.5 Ω + 20 Ω = 27.5 Ω

1 R2,3 = ----- = 7.5 Ω 0.1333

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KIRCHHOFF SERIES/PARALLEL: Parallel

Series

Current

It = I1 + I2 + I3 ....

It = I1=I2 =I3 ....

Voltage

Vt = V1=V2 =V3 ....

Vt = V1 + V2 + V3 ....

POWER EQUATIONS: • • • • • •

E = Pt A = c/s I = Q/t V = J/c V = IR R = V/I

• • • • • •

R = V/I = (J/c) / (c/s) = (J/c) x (s/c) = (Js/c2) R = Js/c2 P = V2/R P = I 2R P=VI w = J/s

READ A HYDROMETER:

•

Each “clock” on the hydrometer represents a digit in a four digit number which, when multiplied by ten, will show the kW consumed

HEAT: • • •

Objects which change temperature either gain or lose heat temperature Heat energy is given the symbol “Q” Heat energy (Q) is determined using the following formula: Q = mcΔT

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Where ◦ m is mass of the material (g) ◦ c is the specific heat capacity of the material (J/gºc) ◦ ΔT is the change in temperature (ºc)

EX: A student heated a certain amount of water (heat capacity of 4.19 J/gºc) in a calorimeter fitted with a resistor and made the following observations during the experiment. How much heat energy is being made. Mass :200g Inital. Temp. : 20ºc Final Temp. : 45ºc Dur. of Experiment : 15m

200g x 4.19J/gºc x 25ºc = 20950 J

HEAT -> ELECTICAL ENERGY: • • • • •

Heat is energy Sometimes, all of the heat generated becomes energy When this is true, E = Q Other times, only a certain percent of the heat is converted to energy When this is true, the following formula is used to determine the % efficiency Q ◦ % Efficiency = -------- X 100 E

CONCENTRATION/SOLUTIONS/DILUTIONS: •

Concentrations can be expressed in three ways: ◦ Mass percent (%) ◦ Concentration in grams per liter (g/L) ◦ Concentration in moles per liter (mol/L)

Solutions and Dilutions •

Solutions can be expressed with the following expression C1 X V1 = C2 X V2

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ACIDS/BASES/SALTS: • •

•

Acids contain at least one hydrogen atom that can be removed when the acid dissolved in water, it therefore can donate H+ ion Bases any substance that form hydroxide ions, OH-, in a water solution is a base. In addition, a base is any substance that accepts H+ from acids. Most bases have a hydroxide ion. Salts neither start with H, nor end with OH: they start with the first part of the formula of a base and end with the last part of the formula of an acid (because they are formed by the neutralization of an acid with a base) ACID + BASE → WATER + SALT

x + yOH →H2O + yx

H

INDICATORS: • • • • • •

An indicator is an organic compound that changes color in an acid or a base Universal Indicators turn a different color at each pH level Most other indicators have one turning point and a total of three different colors A turning point is a usually small range in which the indicator changes color Both before and after the turning point, indicators usually have different colors However, some indicators only have two colors, having the same color for before and after the turning point

pH: • • • • • •

Stands for “power of hydrogen” Scale of acidity or bascicity from 0 to 14 Measure of the concentration of hydrogen ions within a solution Acids have a greater number of H+ ions than OHNeutral (distilled water) contain an equal number of H+ and OH- ions Bases contains less H+ ions than OH- ions

• •

The higher the pH, the more basic it is The lower the pH, the more acidic it is

Concentration Formulas and Equations • • • • •

The [H+] concentration is equal to ten to the power of the negative pH of the substance [H+] = 10-pH The pH of a substance is equal to the negative log of the [H+] concentration pH = -log([H+]) The sum of the [H+] concentration plus the [OH-] concentration is equal to ten to the power of negative fourteen

A.M.D.G ULTIMATE SCIENCE REVIEW • JOSEPH SZYMBORSKI • • •

[H+][OH-]=10-14 [H+]=(10-14 / [OH-] ) [OH-]=( 10-14 / [H+] )

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