chemistry final 2nd Semester

limiting reactant

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a reactant that:

\-is totally consumed in a reaction

\-limits the extent of the reaction

\-determines the amount of product

A reaction stops when one reactant is used up. That reactant is the limiting reactant.

avogadro's number

6\.02 x 10^23

mole

6\.02 x 10^23 particles

representative particle (RP)

the particle being counted

molar mass

the mass in grams of one mole of a pure substance

moles to mass

number of moles x molar mass

m=nM

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molar mass of a compound

the sum of the masses of the particles

that make up one mole of the compound

percent composition

the percent by mass of each element in a compound

molecular formula

the formula with subscripts that are the __actual number of atoms__

empirical formula

the formula with subscripts that are the smallest possible whole-numbers

hydrate

a compound that has a specific number of water molecules bound to its atoms

naming hydrates

**“compound” & “prefixhydrate”** **formula is AX•nH20**

Uses of Hydrates

Na₂SO₄∙10H₂O is used to store solar energy

stoichiometry

the study of quantitative relationships among reactants and products

mole ratio

the ratio between any two substances in a balanced chemical equation

finding mole ratio

4Fe(s)+3O₂(g)→2Fe₂O₃(s)

ratio of number of moles of Fe2O3 to mo moles of Fe

excess reactant

a reactant that remains after the reaction stops

theoretical yield 

the maximum amount of product that can be produced from a given amount of reactant

actual yield 

the amount of product produced when the chemical reaction is carried out in an experiment

percent yield

ratio of actual yield to theoretical yield

kinetic molecular theory

describes behavior of matter in terms of particles in motion

features of kmt (kinetic molecular theory)

1\. __tiny particles__ in lots of __empty space__

2\. __straight line motion__ until they collide with each other or with the walls of the container

3\. __collisions are elastic__

4\. __temperature__ is a measure of __kinetic energy__

elastic collision

a collision in which no kinetic energy is lost

temperature

a measure of the average kinetic energy of the particles in a sample

diffusion

the movement of one material through another from an area of high concentration to an area of low concentration

pressure

force per unit area

gas behavior

space between gas particles decreases as gas compresses.

space between gas particles increases as gas expands.

atmosphere

equals 14.7 psi, or 760 mmHg

pascal

1N/m^2

barometer

an instrument used to measure atmospheric pressure

manometer

an instrument used to measure vapor pressure of a substance

daltons law of partial pressures

total pressure of a mixture of gas is the sum of the pressures of all the gasses in the mixture Ptotal=P1+P2+P3+...Pn

dipole-dipole force

attraction between oppositely charged regions of polar molecules=medium

london dispersion force

weak force resulting from temporary shifts in the density of electrons in the electron cloud=weak

hydrogen bond

A strong dipole-dipole attraction between molecules that contain a hydrogen atom bonded to a small, highly electronegative atom formed only by an H atom bonded to N, O, or F atoms

intramolecular forces

Hold atoms or ions together within a molecule

intermolecular forces

Hold molecules to each other. 

(dipole dipole and london and hydrogen bond)

viscosity

resistance to flow

surface tension

the energy required to increase the surface area of a liquid

allotrope

One of two or more forms of an element with different structures in the same state of matter.

Amorphous solid

A solid whose atoms, ions, or molecules are not arranged in a regular repeating pattern.

Melting point

The temperature at which a crystalline solid becomes a liquid

vaporization

The process by which a liquid changes to a gas or vapor

Boiling point

The temperature at which a liquid becomes a gas

Vapor pressure

The pressure exerted by a vapor over a liquid

evaporation

Vaporization occurring only at the surface of a liquid.

boiling

Vaporization occurring throughout a liquid

sublimation

The process by which a solid changes directly to a gas without first becoming a liquid.

properties of solids

shape: definite \n volume: definite \n expansion on heating: small \n compressibility: no

properties of liquids

particles flow, vaporization, definite volume, assumes the shape of the container, condensed phase, IMFs present disorder of particles

properties of gases

expand to volume of the container, highly compressible, form homogenous mixtures, IMFs nonexistentfc

condensation

The process by which gas becomes a liquid

Freezing point

The temperature at which liquid becomes a crystalline solid

deposition

The process by which substance changes from a gas into a solid without first becoming a liquid.

Phase diagram

A graph of pressure versus temperature that shows the phases of a substance

Triple point

The T and P where solid, liquid, and gas can coexist

six phase changes

melting, vaporizing, condensation, freezing, sublimation, deposition

phase changes that require energy

melting, vaporization, sublimation.

phase changes that release energy

freezing, condensation, deposition.

Critical point

The temperature above which a substance cannot exist at a liquid.

normal melting point

melting point at a pressure of 1 atmosphere

normal boiling point

 the temperature at which the vapour pressure is equal to the standard sea-level atmospheric pressure

cohesion

force of attraction between identical molecules

adhesion

force of attraction between molecules that are different

surfactant

A compound that lowers the surface tension of water

Crystalline solid

A solid whose atoms, ions, or molecules are arranged in an orderly, geometric structure

Unit cell

The smallest arrangement of atoms in a crystal lattice that has the same symmetry as the entire pattern of lattice

boyles law

P₁V₁ = P₂V₂

absolute zero

the lowest possible theoretical temperature

charles's law

V1/T1 = V2/T2

gay-lussac's law

P₁/T₁=P₂/T₂

combined gas law

P₁V₁/T₁ = P₂V₂/T₂

avogadro's principle

equal volumes of gases at same T & P have same number of particles

molar volume

the volume that 1 mole of gas occupies at STP

standard temperature and pressure (STP)

0˚C and 1 atm, 22.4L

ideal gas constant (R)

an experimentally determined constant whose value

depends on the units for pressure (should be given on the test)

ideal gas law

PV = nRT

heterogeneous mixture

a mixture that does not have uniform composition and in which the individual substances remain distinct

suspension

a heterogeneous mixture containing particles that settle out if left undisturbed

thixotropic mixture

a heterogeneous mixture that is viscous at rest but flows when agitated

colloid

a heterogeneous mixture of intermediate-sized particles that do not settle out

dispersion medium

the most abundant substance in a colloid (usually water)

dispersed particles

particles that do not settle out of a colloid

brownian motion

erratic, random movement of dispersed particles caused by collisions with the dispersion medium.

tyndall effect

the scattering of light by dispersed colloid particles

homogeneous mixture:

a mixture that has uniform composition throughout

solution

another word for homogeneous mixture

solute

a substance dissolved in a solution

solvent

the substance that dissolves a solute

soluble

describes a substance that can be dissolved in a solution

insoluble

opposite of soluble

miscible

describes two liquids that are soluble in each other

immiscible

opposite of miscible

mixture

a combination of two or more pure substances that retain their individual chemical properties

concentration

a measure of how much solute is dissolved in a specific amount of solvent or solution

percent by mass

Mass of solute/mass of solution times 100

percent by volume

volume of solute/volume of solution times 100

mole fraction

moles of A/moles of A plus moles of b

molarity

moles of solute/liters of solution times 100

dilution equation

to dilute from concentrated solution to less concentrated solution. M1V1=M2V2