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.