Chemical Reactions Flashcards
is the sum of the atomic weights in atomic mass units (amu) of all the atoms in the compound’s formula. It is used for ionic and molecular compounds.
Formula weight
sum of the atomic weights in atomic mass units (amu) of all the atoms and is used only for covalent compounds
atomic weight
The formula weight of a substance expressed in grams
mol
the amount of any substance that contains as many formula units as the number of atoms in 12 g of carbon-12.
Avogadro’s number (6.022x10^23)
Avogadro’s number from
Amadeo Avogadro
is the formula weight of the substance expressed in grams.
molar mass
reactants that are converted to the products carbon dioxide and water in a chemical reaction called
combustion
A representation using chemical formulas of the process that occurs when reactants are converted to products
chemical reaction
To balance an equation, we place numbers in front of the formulas until the number of each kind of atom in the products is the same as the number in the starting materials. These numbers are called
coefficients
The mass relationships in a chemical reaction
stoichiometry
“Stoichiometry” comes from the Greek
Stoicheion = element; metron = measure
The reactant that is consumed, leaving an excess of another reagent or reagents unreacted
Limiting reagent
A reaction that does not give the main product is called a
Side reaction
The mass of product formed in a chemical reaction
Actual yield
The mass of product that should form in a chemical reaction according to the stoichiometry of the balanced equation
Theoretical yield
The actual yield divided by the theoretical yield times 100
percent yield
ionic compounds always consist of both positive and negative ions. When they dissolve in water, the positive and negative ions become separated from each other by water molecules.
Dissociation
Ions that do not participate in a reaction are called
spectator ions
kind of equation that we write for ions in solution is called a
net ionic equation
is the loss of electrons
oxidation
the gain of electrons.
reduction
involves the transfer of electrons from one species to another
oxidation–reduction reaction/redox reaction
An entity that accepts electrons in an oxidation–reduction reaction
oxidizing agent
An entity that donates electrons in an oxidation–reduction reaction
reducing agent
are redox reactions in which the compounds or mixtures that are burned are oxidized by oxygen, O2.
Combustion
The oxygen in the air we breathe oxidizes carbon-containing compounds in our cells to produce CO2 and H2O.
Respiration
When iron or steel objects are left out in the open air, they eventually rust
Rusting
involves oxidation, and common bleaches are oxidizing agents.
Bleaching
A voltaic cell is a device in which electricity is generated from a chemical reaction.
Batteries
The heat given off or absorbed in a chemical reaction
Heat of reaction
A chemical reaction that gives off heat
Exothermic reaction
A chemical reaction that absorbs heat
Endothermic reaction
The heat given off in a combustion reaction is called the
Heat of combustion
The ionization of acetic acid is written with a double arrow to show that it is a ________; that is, the reaction can occur in both directions.
reversible reaction
results in the formation of an insoluble product, or precipitate
precipitation reaction
an insoluble solid that separates from the solution
precipitate
the formulas of the compounds are written as though all species existed as molecules or whole units
molecular equation
shows dissolved species as free ions
ionic equation
ions that are not involved in the overall reaction
spectator ions
shows only the species that actually take part in the reaction
net ionic equation
as substances that ionize in water to produce H+ ions
acids
substances that ionize in water to produce OH- ions
base
classify substances whose properties in aqueous solutions were well known.
Svante Arrhenius
Notes for acid
*Acids have a sour taste
*Acids cause color changes in plant dyes (Blue to red)
* Acids react with certain metals, such as zinc, magnesium, and iron, to produce hydrogen gas.
* Acids react with carbonates and bicarbonates, such as Na2CO3, CaCO3, and NaHCO3, to produce carbon dioxide gas
* Aqueous acid solutions conduct electricity.
Notes for base
- Bases have a bitter taste
- Bases feel slippery
- Bases cause color changes in plant dyes (red to blue)
- Aqueous base solutions conduct electricity
a proton donor
Bronsted acid
a proton acceptor
Bronsted base
hydrated proton, H3O+, is called the
hydronium ion
each unit of the acid yields one hydrogen ion upon ionization
monoprotic acid
Acids commonly used in the laboratory include
Hydrochloric acid, acetic acid, sulfuric acid, phosphoric acid
each unit of the acid gives up two H+ ions
diprotic acid
yield three H+ ions, are relatively few in number
Triprotic acid
a reaction between an acid and a base
Neutralization reaction
an ionic compound made up of a cation other than H+ and an anion other than OH- or O2-
salt
Whereas acid-base reactions can be characterized as proton-transfer processes, the class
Oxidation-reduction or redox reactions
refers to the half-reaction that involves loss of electrons
Oxidation reaction
half-reaction that involves gain of electrons
Reduction reaction
donates electrons to oxygen and causes oxygen to be reduced
reducing agent
it accepts electrons from calcium, causing calcium to be oxidized
oxidizing agent
signifies the number of charges the atom would have in a molecule (or an ionic compound) if electrons were transferred completely
oxidation number
Rules to assign oxidation number
- In free elements (that is, in the uncombined state), each atom has an oxidation number of zero. Thus each atom in H2, Br2, Na, Be, K, O2, and P4 has the same oxidation number: zero.
- For ions composed of only one atom (that is, monatomic ions) the oxidation number is equal to the charge on the ion. All alkali metals have an oxidation number of +1 and all alkaline earth metals have an oxidation number of +2 in their compounds. Aluminum has an oxidation number of +3 in all its compounds.
- The oxidation number of oxygen in most compounds (for example, MgO and H2O) is -2, but in hydrogen peroxide (H2O2) and peroxide ion (O22-), it is -1.
- The oxidation number of hydrogen is +1, except when it is bonded to metals in binary compounds. In these cases (for example, LiH, NaH, CaH2), its oxidation number is -1.
- Fluorine has an oxidation number of -1 in all its compounds. Other halogens (Cl, Br, and I) have negative oxidation numbers when they occur as halide ions in their compounds.
- In a neutral molecule, the sum of the oxidation numbers of all the atoms must be zero. In a polyatomic ion, the sum of oxidation numbers of all the elements in the ion must be equal to the net charge of the ion.
- Oxidation numbers do not have to be integers.
Four general types of redox reactions
combination reactions, decomposition reactions, displacement reactions, and disproportionation reactions
two or more substances combine to form a single product
Combination reaction
the breakdown of a compound into two or more components
decomposition reaction
an ion (or atom) in a compound is replaced by an ion (or atom) of another element
displacement reaction
Most displacement reactions fit into one of three subcategories:
hydrogen displacement, metal displacement, or halogen displacement
All alkali metals and some alkaline earth metals (Ca, Sr, and Ba), which are the most reactive of the metallic elements, will displace hydrogen from cold water. Less reactive metals, such as aluminum and iron, react with steam to give hydrogen gas
Hydrogen displacement
A metal in a compound can be displaced by another metal in the elemental state.
Metal displacement
a convenient summary of the results of many possible displacement reactions
activity series
Another activity series summarizes the halogens’ behavior in halogen displacement reaction
Halogen displacement
an element in one oxidation state is simultaneously oxidized and reduced.
Disproportionation reaction
the amount of solute present in a given quantity of solvent or solution
concentration of solution
the procedure for preparing a less concentrated solution from a more concentrated one.
Dilution
an analytical technique based on the measurement of mass
gravimetric analysis
the determination of the amount or concentration of a substance in a sample
quantitative analysis
a solution of accurately known concentration
titration
is added gradually to another solution of unknown concentration, until the chemical reaction between the two solutions is complete
standard solution
the point at which the acid has completely reacted with or been neutralized by the base
equivalence point
substances that have distinctly different colors in acidic and basic media
indicators