Chapter 6 Reaction Stoichiometry Libre

Chapter 6 - Reaction Stoichiometry

• Author: Professor McMahon

• Course: General Chemistry I

6.1 Reaction Stoichiometry

Section Objectives

• Explain the concept of stoichiometry in chemical reactions

• Use balanced chemical equations for stoichiometric calculations

• Perform calculations involving mass, moles, and solution molarity

Reaction Stoichiometry Overview

• Definition: Quantitative relationships between amounts of substances in reactions.

• Recipe analogy: Stoichiometry provides the relative amounts of reactants to produce products.

• Example: 1 cup mix + 0.75 cup milk + 1 egg yields 8 pancakes.

Coefficients in Reactions

• Coefficients indicate the number of moles of each substance in a chemical equation.

• Example equation: N2(g) + 3 H2(g) → 2 NH3(g)

Stoichiometric Calculations

• Essential questions:

  • Am I in moles?

  • Am I in the correct chemical?

  • Am I in the right unit?

• Example: How many moles of Ca(OH)2 react with 1.36 moles of H3PO4?

  • Reaction: 3 Ca(OH)2 + 2 H3PO4 → Ca3(PO4)2 + 6 H2O

Mass and Reaction Stoichiometry

• Direct measurement of atoms is impractical; use masses for conversions.

• Convert to moles first, then to mass.

• Example: What mass of Ga2O3 can be prepared from 29.0 g of Ga using the equation: 4 Ga(s) + O2(g) → 2 Ga2O3(s)?

6.2 Limiting Reactant, Theoretical Yield, and Percent Yield

Section Objectives

• Explain theoretical yield and limiting reagents

• Calculate theoretical yields under specific conditions

• Calculate percent yield for reactions

Limiting Reactant

• Definition: Reactant that runs out first, limiting product formation.

• Example analogy: Ingredients for pancakes; having excess of one ingredient.

Theoretical Yield

• Theoretical yield is the predicted amount of product based on limiting reactants, often more than actual yield.

• Percent yield = (actual yield / theoretical yield) × 100%

6.3-6.4 Solution Stoichiometry and Quantitative Analysis

Section Objectives

• Describe titrations and gravimetric analysis fundamentals.

• Perform stoichiometric calculations with typical data.

Quantitative vs. Qualitative Analysis

• Qualitative: Identifies substances present.

• Quantitative: Measures the actual amount/concentration of substances.

Titration Methodology

• Uses stoichiometric relationships to find unknown concentrations in acid-base reactions.

• Monitors neutralization until equivalence point is reached with indicators.

Gravimetric Analysis

• Involves isolating a chemical for measurement through phase change.

• Example: Determining moisture content by weighing before and after heating.

Chemistry in Everyday Life

• Example context: Baking cookies, involving various chemical reactions and processes.