8.2 Chemical Reactions and Stoichiometry - Vocabulary Flashcards

A vocabulary set covering key stoichiometry concepts, balancing rules, and types of chemical reactions from the lecture notes.

Stoichiometry

The branch of chemistry that deals with quantitative relationships between reactants and products in a chemical reaction, using mole ratios to predict amounts formed or consumed.

Law of Conservation of Mass

Matter cannot be created or destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Balanced Chemical Equation

A chemical equation in which the number of atoms of each element is the same on both sides of the equation.

Skeleton Equation

An initial, unbalanced chemical equation that shows correct formulas for reactants and products.

Coefficients

Whole-number factors placed in front of chemical formulas to balance atoms; subscripts inside formulas are not changed.

Subscripts

Numbers within chemical formulas indicating the number of atoms in a molecule; they must not be altered when balancing equations.

Mole

The amount of substance containing 6.022 × 10^23 particles, used to count atoms and molecules in chemistry.

Avogadro's Number

6.022 × 10^23 particles per mole; enables conversion between moles and number of particles.

Molar Mass

Mass per mole of a substance (g/mol); used to convert between mass and moles.

STP (Standard Temperature and Pressure)

0°C and 1 atm; at STP, one mole of an ideal gas occupies 22.4 L.

Molar Volume at STP

22.4 L per mole, the volume occupied by one mole of an ideal gas at STP.

Mole Ratio

The proportional relationship between amounts (in moles) of reactants and products in a balanced equation.

Limiting Reactant

The reactant that is completely consumed first, limiting the amount of product that can form.

Excess Reactant

The reactant that remains after the reaction has reached completion because the limiting reactant was consumed first.

Percent Yield

Actual yield divided by theoretical yield, multiplied by 100%; measures reaction efficiency.

Ideal Gas Law

PV = nRT, relating pressure, volume, amount of gas, and temperature for gases.

PV = nRT

The equation of state for ideal gases, where P is pressure, V is volume, n is moles, R is the gas constant, and T is temperature.

Gas Stoichiometry

Applying stoichiometric calculations specifically to gases, often using molar volume or the ideal gas law.

Synthesis (Combination) Reaction

Two or more reactants form a single product (A + B → AB).

Decomposition Reaction

A compound breaks down into two or more simpler substances (AB → A + B).

Single Displacement (Replacement) Reaction

One element replaces another in a compound (A + BC → AC + B).

Double Displacement (Replacement) Reaction

Ions in two compounds exchange places (AB + CD → AD + CB).

Combustion Reaction

A hydrocarbon reacts with oxygen to produce CO2 and H2O (fuel + O2 → CO2 + H2O).

Redox (Oxidation-Reduction) Reaction

Reactions involving transfer of electrons; oxidation states change and half-reactions may be balanced separately.

Oxidation Number

A bookkeeping value assigned to an element in a compound that reflects its oxidation state.

Oxidation

Increase in oxidation state, typically loss of electrons.

Reduction

Decrease in oxidation state, typically gain of electrons.

Atom Counting

Tallying the number of atoms of each element on both sides of a chemical equation to balance it.

Balancing Rule: Subscripts cannot be changed

When balancing, the subscripts in formulas must not be altered, only coefficients may be adjusted.

Unbalanced vs Balanced Equation

Unbalanced: atoms are not equal on both sides; Balanced: atoms are equal on both sides, obeying the Law of Conservation of Mass.