Aleks Module Answers

Question: Fahrenheit Equation

Answer: Tf=(Tc x 9℉/5℃) + 32℉

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Question: Celsius Equation

Answer: Tc= 5℃/9℉ (Tf - 32℉)

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Question: More Equations

Answer: Ep=h x v
c=weird symbol x v

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Question: Average Velocity of a Gas Particle

Answer: Vrms = square root (3RT/MM)

R= gas law constant
T= temperature
MM= molar mass of gas particles

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Question: Base for log

Answer: It is 10
10^5
log10(100,000)=5

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Question: Base for ln

Answer: e
Euler's number

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Question: Rules for Counting Significant Figures

Answer: 1. Any non-zero digit in a measurement is significant (11325 has 5 sig figs)

2. Zeros between non-zero digits are considered significant (4003 has 4 sig figs)

3. Zeros to the left of the first non-zero digit are insignificant (0.072 has 2 sig figs)

4. Zeros to the right of the non-zero digits are significant only when the number contains a decimal point (400.0g has 3 sig figs whereas 400g only has 1 sig fig)

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Question: Form of Scientific Notation

Answer: N x 10^M
N is a number between 1.000 and 9.999
Ex: 400 = 4.0 x 10^2

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Question: Rules for Using Significant Figures

Answer: Multiplication/Division: must have same number of sig figs as lowest number

Addition/Subtraction: last common place rule

Logarithms: numbers after decimal are significant. Round answer to whole

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Question: SI Prefixes

Answer: Factor = Prefix
10^12 = tera (T)
10^9 = giga (G)
10^6 = mega (M)
10^3 = kilo (K)
10^-2 = centi (c)
10^-3 = milli (m)
10^-6 = micro (µ)
10^-9 = nano (n)
10^-12 = pico (p)
10^-15 = femto (f)

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Question: Rule of Thumb for Prefix Conversion

Answer: If the prefix gets smaller, the number should get bigger. If the prefex gets bigger, the number should get smaller.

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Question: Conversion Factor

Answer: an equality showing the same measurement expressed in two different units

Some conversion factors:
1 ft = 12 in
2.54 cm = 1 in
3.785 L = 1 gallon

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Question: Celsius to Kelvin Equation

Answer: K = ℃ + 273.15

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Question: Kelvin to Celsius Equation

Answer: C = K - 273.15

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Question: Freezing Point of water on the Kelvin scale

Answer: 273.15

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Question: Density

Answer: the ratio of the mass of a substance contained in its volume

D = M/V

Density Units:
Solid; g/cm^3
Liquid; g/mL
Gas; g/L

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Question: Scientific Method

Answer: Process of studying natural phenomenon

Steps:
Making onservations --> Forming hypotheses --> Preforming experiments

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Question: Qualitative Observation

Answer: Subjective and can be made using one of the five senses

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Question: Quantitative Observation

Answer: objective and involves a number and a unit

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Question: Hypothesis

Answer: proposed explanation for a phenomenon that can be tested

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Question: Dependent Variable

Answer: a variable (often denoted by y) whose value depends on that of another.

There is always one

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Question: Independent Variable

Answer: a variable (often denoted by x ) whose variation does not depend on that of another.

There is 1+

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Question: Experiment

Answer: determines the effect on the dependent variable when a change is made to an independent variable.

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Question: Scientific Theory

Answer: gives an overall explanation of a natural phenomenon (why/how something happens)

Analytical statement

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Question: Natural Law

Answer: explains behavior when the same observations occur repeatedly through an extensive set of experiment

calculates what happened

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Question: Matter

Answer: anything that has mass and takes up space

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Question: Solid

Answer: definite shape/volume

particles have least amount of energy and are fixed in place

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Question: Liquid

Answer: definite volume

no specific shape

particles = more energy

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Question: Gas

Answer: no definite shape/volume

particles have most energy

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Question: Pure Substance

Answer: consists of matter that has a fixed or constant composition

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Question: Compound

Answer: Ex: H2O

Can be chemically separated into elements

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Question: Elements

Answer: Ex: H2, O2

Combine chemically to create compounds

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Question: Mixture

Answer: composed of 2+ pure substances in any physical state

Variable composition

Can be physically separated into their composite substances

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Question: Homogeneous Mixture

Answer: uniform composition throughout mixture sample

solutions

gas, metal alloys, and air

all homogeneous mixtures exist in a single phase

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Question: Heterogeneous Mixture

Answer: consists of components which have localized regions of each pure substance within the mixture

Ex: supreme pizza. Distribution of ingredients = not uniform

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Question: Property

Answer: any characteristic that can be used to describe or identify matter

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Question: Chemical Property

Answer: involve a change in the sample's chemical make-up

Example: the heat of combustion of a substance determines how much heat is released when a particular substance is burned

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Question: Physical Property

Answer: attributes that can be measured without changing the sample's chemical make-up

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Question: Extensive Property

Answer: depends on the amount of matter in the sample

examples: size, shape, mass, and volume

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Question: Intensive Property

Answer: does NOT depend on the amount of matter in the sample

examples: ductility, malleability, density, color, and boiling point (but, when stretching gold, overall length and diameter are extensive properties)

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Question: Physical Change

Answer: occur between any 3 state of matter and all changes are intensive

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Question: Physical States and Phase Changes

Answer: Solid sublimation to gas, gas condensation to liquid, liquid to freezing solid.

Solid melting to liquid, liquid vaporization to gas, gas sublimation to solid.

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Question: Distillation

Answer: utilized to separate different liquids from a solution based upon their boiling point.

substances with lowest boiling point will vaporize first

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Question: Filtration

Answer: utilized to separate a heterogeneous mixture that consists of a solid and a liquid.

poor mixture over filtration paper, paper catches solid, liquid passes through paper

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Question: Chromatography

Answer: utilized to separate components of a liquid solution of a gaseous solutions.

utilizes 2 different states of matter
-stationary phase - solid
-mobile phase - liquid or gas

components separate depending on their similarity or affinity for each phase
-high affinity for mobile = move quickly through chromatography

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Question: John Dalton's Four Major Claims about the Nature of Atoms

Answer: 1. Elements are made of atoms.

2. Atoms of each element are identical to each other, but different from the atoms of other elements.

3. Chemical compounds are formed by atoms of different elements coming together in a fixed ratio.

4. Chemical reactions involve the reorganization of atoms moving from one compound to another.

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Question: Antoine Lavoisier

Answer: experimental verification of the Law of Conservation of Mass (mass is not created nor destroyed in chemical reaction)

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Question: Joseph Proust

Answer: Law of Definite Proportions (a given compound always contatins exactly the same ratio of elements, by mass)

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Question: John Dalton

Answer: Law of Multiple Proportions (whenever 2 elements form a series of compounds, the ratios of the masses of the second element that combine with exactly one gram of the first element can always be reduced to small, whole numbers)

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Question: J.J. Thomson

Answer: Cathode Ray Tubes Experiment

Discovered electrons
Charge to mass ratio: 1g e^- = -1.76 x 10^8 C

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Question: Robert Millikan

Answer: Oil Drop Experiment

Mass: 9.11 x 10^-31 kg

Discovered the charge of electrons:
1 electron = -1.60 x 10^-19 C

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Question: Ernest Rutherford

Answer: Gold Foil Experiment

Discovered the nucleus

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Question: James Chadwick

Answer: Beryllium Bombardment Experiment

Discovered neutrons

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Question: Periodic Table

Answer: Dmitri Mendeleev (1872)

Period: rows - order
Group: columns - contain elements with similar properties and reactivities

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Question: Group Names

Answer: Group 1A: Alkali Metals (highly reactive solids (salts))

Group 2A: Alkaline Earth Metals (reactive solids, create alkaline solutions in water)

Group 5A: Pnictogen ("choking")

Group 6A: Chalcogens ("born from copper")

Group 7A: Halogens (reactive and form metal when exposed to salt) ("salt forming")

Group 8A: Nobel Gases (rarely react, all gases)

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Question: Elemental Symbol

Answer: shiny, malleable, ductile, lose electrons easily

1A, 2A, not Hydrogen, transition, rare earth elements, Al, Ga, In, Tl, Sn, Pb, and Bi

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Question: Metal

Answer: more likely to gain electrons, exist in all three states

Hydrogen and elements in right corner, C, N, o, P, S, Se, 7A, and 8A

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Question: Nonmetal

Answer: all solid, hold properties of both

B, Si, Ge, As, Sb, Te

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Question: Metalloid

Answer: way atoms are arranged in element

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Question: Allotrope

Answer: elements that exist in pairs of atoms

Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, Iodine, Hydrogen

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Question: Diatomic

Answer: an atom/molecule with a net charge due to loss/gain of electrons

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Question: Ion

Answer: positive (lose electrons)

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Question: Cation

Answer: negative (gain electrons)

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Question: Anion

Answer: Group 1A: 1+ Cation

Group 2A: 2+ Cation

Group 3A: 3+ Cation

Group 5A: 3- Anion

Group 6A: 2- Anion

Group 7A: 1- Anion

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Question: Ionic Charges for each Group

Answer: Fe^2+ = iron (II) ion
Mn^4+ = Manganese (IV) ion
Cl^- = Chloride
O^2- = Oxide

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Question: Examples of Naming Ions

Answer: make flashcards by hand

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Question: Polyatomic Ions

Answer: make flashcards by hand

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Question: Ionic Nomenclature

Answer: made from 2+ atoms

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Question: Molecule

Answer: Look at the type of atom used to make them

Ionic:
Metal and nonmetal or at least one polyatomic ion
Fixed ratio of ions

Covalent: only nonmetals

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Question: How can you determine if a compound is ionic or covalent?

Answer: Number of Atoms = Prefix

1 = Mono
2 = Di
3 = Tri
4 = Tetra
5 = Penta
6 = Hexa
7 = Hepta
8 = Octa
9 = Nona
10 = Deca

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Question: Prefixes for Naming Covalent Compounds

Answer: NO = nitrogen monoxide
NO2 = nitogen dioxide
N2O = dinitrogen monoxide
N2O4 = dinitrogen tetroxide

Boron trichloride = BCl3
Tetraphophorus heptasulfide = P4S7

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Question: Examples of Naming Covalent Compounds

Answer: atoms of the same element with different numbers of neutrons

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Question: Isotope

Answer: Carbon-12

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Question: Isotopic Symbols

Answer: look at notes

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Question: What isotope is the standard for the atomic mass unit (amu)?

Answer: the amount of a chemical substance that contains as many representative particles, atoms, etc as there are atoms in exactly 12g of Carbon-12

1 atom ^12C = 12 amu
12.01gC = 1 mol C
1 mol ^12C = 12g ^12C

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Question: How to solve for average atomic mass of elements and percent abundances of elemental isotopes

Answer: NA = 6.022 x 10^23g

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Question: Mole

Answer: 12 amu

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Question: Avagrado's Number

Answer: 12.01g

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Question: Atomic Mass of ^12C

Answer: substances you have before the chemical equation

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Question: Molar Mass of Carbon

Answer: formed during chemical reactions

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Question: Reactants

Answer: 1. Write the correct formula(s) for the reactants on the left side of the arrow and the correct formula(s) for the products on the right side of the equation.

2. Change the numbers IN FRONT of the formulas (called coefficients) to make the number of atoms of each element the same on both sides of the equations.
DO NOT CHANGE THE SUBSCRIPTS

3. Balance those elements that are in the more complex compounds (polyatomic-containing ionic compounds or large covalent compounds)
CHECK TO SEE IF POLYATOMIC IONS STAY TOGETHER

4. Balance the simple compounds last (molecular diatomics or single elements)

5. Check to make sure that the same number of each type of atom is equivalent on both sides

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Question: Products

Answer: grams

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Question: Rules for Balancing Chemical Equations

Answer: Particles --(Avagrado's #)--> moles --(molar mass)--> mass

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Question: What are the units of molar mass?

Answer: Coefficients in a chemical equation tell us the ration of how reactants are used up and how products are formed

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Question: Mass to Mole to Particle Conversions

Answer: 1. Have a balanced chemical equation. If you do not already have a balanced chemical equation, this will always be your first step in a stoichiometric calculation.

2. Convert the sample's mass into moles. This can be done using molar mass of the original species.

3. Convert the moles of you known species into moles of your desired compound. We can do this by using the coefficients in the balanced equation as a molar ratio.

(mol of what you want) / (mol of what you had)

4. Convert the moles of target compound into mass using its molar mass.

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