Chapter 7: Stoichiometry of Chemical Reactions

chemical equations

reactants ———→ products

balancing equations

equal amounts of each element on each side of the equation (don’t change subscripts)

types of reactions

combination, decomposition, single replacement, double replacement, combustion

combination

A + B = AB

decomposition

AB = A + B

single replacement

A + BC = AC + B

double replacement

AB + CD = AD + CB

combustion

C_xH_y + H⁺ = Zn²⁺ + H₂

precipitation rx

reaction that results in a form of insoluble product; a type of double displacement reaction (results in solid product)

acid-base Rx

neutralization

redox Rx

electron transfer (type of single displacement)

molecular equation

shows complete chemical formulas of reactants and products

complete ionic equation

shows dissolved species of free ions

spectator ions

present but play no role in the reaction (appear on both sides of the reaction)

net ionic equation

shows only species that take part in the reaction (cancel out spectator ions on both sides)

Soluble

contains group 1A cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, or NH₄⁺), anions (Cl-, Br-, I-, NO₃^-, Cl₄^-, CH₃CO₂^-, or SO₄²⁺)

Insoluble

CO₃^2-, PO₄^3-, CrO₄^-, S^2-, OH-

Acids

substances that ionize in aqueous solutions to form H⁺ ions

Monoprotic acid

each unit of acid yields one hydrogen ion (H⁺)

Diprotic acid

each unit of acid yields 2 H⁺ ions

Triprotic acid 

each unit of acid yields 3 H⁺ ions

Bases

increase OH^- concentration in water; accept protons (H⁺), all group 1A hydroxides

Strong acids

HCL, HBr, HI, HNO₃, H₂SO₄, HClO₄

Weak bases

most common is NH₄ (ammonia), others are derivatives of ammonia 

Neutralization reaction

solution of acid and base mixed together to form salt and sometimes water (if the base is strong)

Oxidation reduction reaction

loss of electrons = oxidation, gain electrons = reduction; they always come together because electrons transfer 

OIL- RIG

Oxidation is loss - reduction is gain

Hydrogen oxidation numbers

+1 with non metals, -1 with metals

Oxygen oxidation numbers

-2 in most compounds, sometimes -1 (peroxides)

Halogen oxidation numbers

F is always -1, -1 for others except when paired with oxygen or other halogens

Max oxidation #

group #

Min oxidation #

group # - 8

What substance is the reducing agent?

the substance that is oxidized

What substance is the oxidizing agent

the substance that is reduced

Hydrogen displacement

alkali metals and some alkaline earth metals react with water

Stoichiometry

use coefficients to find the # of moles and then grams of a substance

Limiting reagent

reagent that gives the lesser amount of product; limits the amount of product that can form

Theoretical yield

quantity of a product calculated to be produced

Actual yield

amount of product obtained during a reaction

Gravimetric analysis

an analytical technique based on measurement of mass (uses gravity to drain a solution)

Acid base titration

procedure for determining the concentration of a solution using another solution of known concentration