Stoichiometry and Dimensional Analysis

Using Molar Mass and Mole Ratios

Stoichiometry involves quantitative relationships between reactants and products in a chemical reaction. Dimensional analysis is used to convert between units, such as grams to moles, using molar mass and mole ratios from balanced equations.

• Molar Mass: The mass of one mole of a substance, expressed in grams per mole (g/mol).

• Mole Ratio: The ratio of coefficients from a balanced chemical equation, used to relate amounts of reactants and products.

• Dimensional Analysis: A method to convert between units using conversion factors.

Example: For the reaction , the mole ratio between and is 1:1.

Key Equations:

• To convert grams to moles:

• To use mole ratios:

Limiting Reactant and Reaction Completion

The limiting reactant is the substance that is completely consumed first in a chemical reaction, thus determining the maximum amount of product formed. After the reaction, some reactants may remain (excess reactants).

• Limiting Reactant: The reactant that runs out first and limits the amount of product.

• Excess Reactant: The reactant(s) left over after the reaction is complete.

• Product Formed: Determined by the amount of limiting reactant.

Steps to Find Limiting Reactant:

1. Convert all reactant quantities to moles.

2. Use mole ratios to determine which reactant produces the least amount of product.

3. The reactant that produces the least product is the limiting reactant.

Example: If 5.0 g of reacts with 10.0 g of , calculate which is limiting and how much is formed.

Equation for Remaining Excess Reactant:

Balancing Chemical Equations

Principles of Balancing

Balancing chemical equations ensures the law of conservation of mass is obeyed: the number of atoms of each element is the same on both sides of the equation.

• Steps:

  1. Write the unbalanced equation.

  2. Count atoms of each element on both sides.

  3. Add coefficients to balance atoms (do not change subscripts).

  4. Check your work.

Example: Balance

• Balanced:

Naming Chemical Compounds

Naming Ionic Compounds

Ionic compounds are formed from metals and nonmetals. The name consists of the cation (metal) followed by the anion (nonmetal with -ide ending).

• Binary Ionic Compounds: Name the metal, then the nonmetal with -ide.

• Transition Metals: Indicate the metal's charge with Roman numerals.

Examples:

• – sodium chloride

• – iron(III) chloride

Naming Covalent (Molecular) Compounds

Covalent compounds are formed between nonmetals. Prefixes indicate the number of each atom.

• Prefixes: mono-, di-, tri-, tetra-, penta-, hexa-, etc.

• First element: Prefix only if more than one atom.

• Second element: Always use a prefix and end with -ide.

Examples:

• – carbon dioxide

• – dinitrogen pentoxide

Summary Table: Naming Compounds