Balancing equations, predicting yields and analyzing samples. Learn the language of how substances react and how much they produce.
These terms were extracted from Chemistry by OpenStax, eCampusOntario (© 2016 Rice University; adapted by BCcampus) which is licensed under a Creative Commons Attribution 4.0 International License.
Download this book for free here
chemical equation with equal numbers of atoms for each element in the reactant and product
These coefficients yield equal numbers of both H and O atoms on the reactant and product sides, and the balanced equation is, therefore:
symbolic representation of a chemical reaction
Derive chemical equations from narrative descriptions of chemical reactions.
number placed in front of symbols or formulas in a chemical equation to indicate their relative amount
The relative numbers of reactant and product species are represented by coefficients (numbers placed immediately to the left of each formula).
chemical equation in which all dissolved ionic reactants and products, including spectator ions, are explicitly represented by formulas for their dissociated ions
Explicitly representing all dissolved ions results in a complete ionic equation.
chemical equation in which all reactants and products are represented as neutral substances
This balanced equation, derived in the usual fashion, is called a molecular equation because it doesn’t explicitly represent the ionic species that are present in solution.
chemical equation in which only those dissolved ionic reactants and products that undergo a chemical or physical change are represented (excludes spectator ions)
This net ionic equation indicates that solid silver chloride may be produced from dissolved chloride and silver(I) ions, regardless of the source of these ions.
substance formed by a chemical or physical change; shown on the right side of the arrow in a chemical equation
Igniting the mixture initiates a vigorous chemical reaction that rapidly generates large amounts of gaseous products.
substance undergoing a chemical or physical change; shown on the left side of the arrow in a chemical equation
The substances undergoing reaction are called reactants, and their formulas are placed on the left side of the equation.
ion that does not undergo a chemical or physical change during a reaction, but its presence is required to maintain charge neutrality
Finally, identify the spectator ion(s), in this case Na⁺(aq), and remove it from each side of the equation to generate the net ionic equation:
substance that produces H₃O⁺ when dissolved in water
In this context, an acid is a substance that will dissolve in water to yield hydronium ions, H₃O⁺.
reaction involving the transfer of a hydrogen ion between reactant species
An acid-base reaction is one in which a hydrogen ion, H⁺, is transferred from one chemical species to another.
substance that produces OH⁻ when dissolved in water
A base is a substance that will dissolve in water to yield hydroxide ions, OH⁻.
vigorous redox reaction producing significant amounts of energy in the form of heat and, sometimes, light
In combustion reactions, a fuel and an oxidant react vigorously and produce significant amounts of heat, and often light, in the form of a flame.
an equation that shows whether each reactant loses or gains electrons in a reaction.
It is helpful to view the process with regard to each individual reactant, that is, to represent the fate of each reactant in the form of an equation called a half-reaction:
of relatively low solubility; dissolving only to a slight extent
Substances with relatively low solubilities are said to be insoluble, and these are the substances that readily precipitate from solution.
reaction between an acid and a base to produce salt and water
A neutralization reaction is a specific type of acid-base reaction in which the reactants are an acid and a base, the products are often a salt and water, and neither reactant is the water itself:
process in which an element’s oxidation number is increased by loss of electrons
To clarify the similarity of this reaction to the previous one and permit an unambiguous definition of redox reactions, a property called oxidation number has been defined.
(also, redox reaction) reaction involving a change in oxidation number for one or more reactant elements
In the reaction of sodium with chlorine, sodium is oxidized and chlorine undergoes reduction, so it is an oxidation-reduction (redox) reaction.
(also, oxidation state) the charge each atom of an element would have in a compound if the compound were ionic
To clarify the similarity of this reaction to the previous one and permit an unambiguous definition of redox reactions, a property called oxidation number has been defined.
(also, oxidant) substance that brings about the oxidation of another substance, and in the process becomes reduced
Likewise, chlorine functions as an oxidizing agent (oxidant), as it effectively removes electrons from (oxidizes) sodium.
insoluble product that forms from reaction of soluble reactants
A substance will precipitate when solution conditions are such that its concentration exceeds its solubility.
reaction that produces one or more insoluble products; when reactants are ionic compounds, sometimes called double-displacement or metathesis
A precipitation reaction is one in which dissolved substances react to form one (or more) solid products.
process in which an element’s oxidation number is decreased by gain of electrons
In this reaction, then, sodium is oxidized and chlorine undergoes reduction.
(also, reductant) substance that brings about the reduction of another substance, and in the process becomes oxidized
Viewed from a more active perspective, sodium functions as a reducing agent (reductant), since it provides electrons to (or reduces) chlorine.
ionic compound that can be formed by the reaction of an acid with a base that contains a cation and an anion other than hydroxide or oxide
The solubility guidelines indicate all nitrate salts are soluble but that AgF is one of the exceptions to the general solubility of fluoride salts.
(also, replacement) redox reaction involving the oxidation of an elemental substance by an ionic species
When a strip of zinc is placed in copper(II) sulfate solution, zinc replaces copper in a single-displacement reaction.
of relatively high solubility; dissolving to a relatively large extent
Substances with relatively large solubilities are said to be soluble.
the extent to which a substance may be dissolved in water, or any solvent
A substance will precipitate when solution conditions are such that its concentration exceeds its solubility.
acid that reacts completely when dissolved in water to yield hydronium ions
Acids that completely react in this fashion are called strong acids, and HCl is one among just a handful of common acid compounds that are classified as strong (Table 9).
base that reacts completely when dissolved in water to yield hydroxide ions
These bases, along with other hydroxides that completely dissociate in water, are considered strong bases.
acid that reacts only to a slight extent when dissolved in water to yield hydronium ions
A familiar example of a weak acid is acetic acid, the main ingredient in food vinegars:
base that reacts only to a slight extent when dissolved in water to yield hydroxide ions
In all cases, these compounds react only partially and so are classified as weak bases.
ratio of coefficients in a balanced chemical equation, used in computations relating amounts of reactants and products
The coefficients in the balanced equation are used to derive stoichiometric factors that permit computation of the desired quantity.
relationships between the amounts of reactants and products of a chemical reaction
These quantitative relationships are known as the reaction’s stoichiometry, a term derived from the Greek words stoicheion (meaning “element”) and metron (meaning “measure”).
amount of product formed in a reaction
In practice, the amount of product obtained is called the actual yield, and it is often less than the theoretical yield for a number of reasons.
reactant present in an amount greater than required by the reaction stoichiometry
This substance is the limiting reactant, and the other substance is the excess reactant.
reactant present in an amount lower than required by the reaction stoichiometry, thus limiting the amount of product generated
This substance is the limiting reactant, and the other substance is the excess reactant.
measure of the efficiency of a reaction, expressed as a percentage of the theoretical yield
The extent to which a reaction’s theoretical yield is achieved is commonly expressed as its percent yield.
amount of product that may be produced from a given amount of reactant(s) according to the reaction stoichiometry
Derive the theoretical yield for a reaction under specified conditions.
chemical species of interest
Also common are gravimetric techniques in which the analyte is subjected to a precipitation reaction of the sort described earlier in this chapter.
device used for the precise delivery of variable liquid volumes, such as in a titration analysis
A typical titration analysis involves the use of a buret to make incremental additions of a solution of known concentration.
gravimetric technique used to determine the elemental composition of a compound via the collection and weighing of its gaseous combustion products
The elemental composition of hydrocarbons and related compounds may be determined via a gravimetric method known as combustion analysis.
measured volume of titrant solution that yields the change in sample solution appearance or other property expected for stoichiometric equivalence (see equivalence point)
Regardless of the approach taken to detect a titration’s equivalence point, the volume of titrant actually measured is called the end point.
volume of titrant solution required to react completely with the analyte in a titration analysis; provides a stoichiometric amount of titrant for the sample’s analyte according to the titration reaction
The equivalence point of a titration may be detected visually if a distinct change in the appearance of the sample solution accompanies the completion of the reaction.
quantitative chemical analysis method involving the separation of an analyte from a sample by a physical or chemical process and subsequent mass measurements of the analyte, reaction product, and/or sample
The required change of state in a gravimetric analysis may be achieved by various physical and chemical processes.
substance added to the sample in a titration analysis to permit visual detection of the end point
Special dyes called indicators are added to the sample solutions to impart a change in color at or very near the equivalence point of the titration.
the determination of the amount or concentration of a substance in a sample
The test of vinegar with potassium carbonate is one type of quantitative analysis—the determination of the amount or concentration of a substance in a sample.
solution containing a known concentration of substance that will react with the analyte in a titration analysis
Regardless of the approach taken to detect a titration’s equivalence point, the volume of titrant actually measured is called the end point.
quantitative chemical analysis method that involves measuring the volume of a reactant solution required to completely react with the analyte in a sample
The described approach to measuring vinegar strength was an early version of the analytical technique known as titration analysis.