Unit 4: Chemical Reactions

physical changes

a change in the form or appearance of a substance, but not its chemical composition

chemical change

change in the chemical composition of a substance

reactants

chemical species that are present before a reaction occurs

products

chemical species that are present after a reaction occurs

synthesis reaction

reaction in which two or more reactants combine to form a single product

decomposition reaction

reactions in which a single reactant breaks down into two or more products

single replacement reaction

reactions in which an element in a compound is replaced by another element

double replacement reaction

reactants in which two elements in different compounds exchange places to form new compounds

combustion reaction

reactions in which a fuel reacts with oxygen to produce heat, light, and various products such as water and carbon dioxide

dissociation

process of a molecule breaking into ions in a solution

insoluble

a substance does not dissolve in a particular solvent

spectator ions

ions that are present in a chemical reaction, but do not participate in the transfer of electrons or protons

net ionic eqution

chemical equation that shows only the species that are involved in a chemical reaction, and not the spectator ions

complete ionic equation

chemical equation that shows all of the ions that are present in a solution including the spectator ions

balanced equation

equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products

law of conservation of mass

states that matter cannot be created or destroyed in an isolated system. in other words, the total mass before a chemical reaction is equal to the totals mass after the reaction

chemical processess

process that involves the breaking and/or formation of chemical bonds

physical processes

process that involves only changes in intermolecular interactions, such as phase changes

stoichiometry

study of the relationships between the reactants and products in a chemical reaction

limiting reactant

reactant that is completely used up in a chemical reaction, limiting the amount of product that can be formed

excess reactant

reactant that still exists in solution after the chemical reaction is complete

titration

laboratory technique used to determine the unknown concentration of a solution by adding a known concentration of another solution

equivalence point

point at which the number of moles of the titrant (solution being added) is equal to the number of moles of the analyte (solution being analyzed)

end point

signifies the completion of the titration by a change in the color or intensity of the solution, typically due to the addition of an indicator

indicator

typically is a weak acid or weak base that has different colors in its dissociated and undissociated form that reacts with an acid or base to show an end point in a titration

acid-base reactions

also known as neutralization reactions, these involve an acid reacting with a base to produce water plus a salt

oxidation-reduction reactions

these reactions involve the transfer of electrons between chemical species. substance losing electrons is being oxidized while the one gaining electrons is being reduced

oxidation number

hypothetical charge of an atom if all of its bonds to other atoms were fully ionic. it is also a number assigned to an element which represents the number of electrons lost or gained to form a chemical bond with another atom

precipitation reactions

chemical reactions that result in the formation of an insoluble product, or precipitate, when two solutions are mixed

bronsted-lowry acid

any species that can donate a proton

bronsted-lowry base

any species that can accept a proton

conjugate acid

chemical compound formed when an acid gives a proton to base, in other words, it is a base with a hydrogen ion added to it

conjugate base

chemical compound formed by the removal of a proton from an acid

oxidation

occurs when an atom, molecule, or ion loses one or more electrons in a chemical reaction

reduction

process of an atom or compound gaining one or more electrons

half-reaction

part of an overall reaction that represents, separately, either an oxidation or a reduction

evidence of physical change

change in state

evidence of chemical change

color change, gas production, light production, temperature change, precipitation, odor/oxidation

acetate

CH₃COO^1-

ammonium

NH₄¹⁺

bicarobante

HCO₃^1-

carbonate

CO₃^2-

chlorate

ClO₃^1-

dichromate

Cr₂O₇^2-

hydroxide

OH^-

nitrate

NO₃^1-

permanganate

MnO₄^1-

phosphate

PO₄^3-

sulfate

SO₄^2-

sodium, nitrate, ammonium, potassium, lithium (SNAPL)

substances are sollube and will never form a precipitate when they contain these

percent yield formula

(actual yield/theoretical yield) x 100

percent yield

a way to describe how close an experimental yield is to the amount predicted

tirtant

solution being added to a flask out of a buret

analyte

solution being analyzed in a flask

titration curve

used to determine the equivalence point of a titration. the point on this where pH change is greatest indicates the volume needed to react with the analyte

amphiprotic

substances that can act as an acid or a base (ex: water)

redox mnemonic

leo the lion says ger

chloric acid

HClO₃

hydrobromic acid

HBr

hydrochloric acid

HCl

hydroiodic acid

HI

nitric acid

HNO₃

perchloric acid

HClO₄

sulfuric acid

H₂SO₄

lithium hydroxide

LiOH

sodium hydroxide

NaOH

potassium hydroxide

KOH

rubidium hydroxide

RbOH

calcium hydroxide

Ca(OH)₂

strontium hydroxide

Sr(OH)₂

barium hydroxide

Ba(OH)₂

elements

have an oxidation number of 0

monoatomic ions

have oxidation number equal to the charge of the ion

oxygen in a compound

has an oxidation number of -2 (besides peroxides)

oxygen in peroxide

has an oxidation number of -1

hydrogen in a compound

has an oxidation number of +1 (besides hydrides)

hydrogen in hydrides

has an oxidation number of -1

atoms in group 1

have an oxidation number of +1

atoms in group 2

have an oxidation number of +2

more electronegative atom

given the oxidation state of its species (its common ion)

fluroine

has an oxidation number of -1

long chemical reaction arrow

points towards more favored side, away from strong acids

peroxide

group 1 metal with O₂ not simplified

hydride

metal with H

strong acid/base

weak conjugate