Chapter9FirstSection

Testing Advertising Claims

• Work for a consumer advocate organization

• Test company claims about antacid effectiveness:

  • Company claims: Product neutralizes 10x as much stomach acid per tablet compared to competitor.

  • Testing Method: Conduct experiments to compare acid neutralization capacity of both antacids.

Manufacturing Methanol

• Working for a chemical company making methanol (methyl alcohol).

  • Methanol is used for antifreeze, aviation fuels, and racing fuel (e.g., Indianapolis 500).

  • Task: Order hydrogen and carbon monoxide to produce 6.0 kg of methanol.

  • Determination: Use stoichiometry to find the exact quantities needed.

Chemical Equations

Importance

• Chemistry involves chemical reactions characterized by rearrangements of atoms.

• Reaction Equations: Describe reactants and products involved, and quantify their amounts through coefficients.

Analogy with Sandwich Making

• Sandwich Example:

  • Components: 2 pieces bread, 3 slices meat, 1 slice cheese for 1 sandwich.

  • For 50 sandwiches:

    • Multiply ingredients by 50: 100 pieces bread, 150 slices meat, 50 slices cheese.

Balancing Chemical Equations

Example with Methanol Production

• Unbalanced equation:

  • CO(g) + H2(g) → CH3OH(l)

• Balance Equation:

  • CO(g) + 2H2(g) → CH3OH(l)

  • Check atoms: Reactants:C:1, O:1, H:4; Products: C:1, O:1, H:4.

• Coefficients: Represent relative numbers of molecules.

Application of Moles

• Introduce the mole concept using Avogadro's number (6.022 × 10^23).

• Example Equation:

  • CO(g) + 2H2(g) → CH3OH(l) becomes:

  • 1 mol CO + 2 mol H2 → 1 mol CH3OH

Mole-Mole Relationships

Example with Water Decomposition

• Balanced equation:

  • 2H2O(l) → 2H2(g) + O2(g)

• Calculation of Products from Reactants:

  • 4 mol of H2O yields 4 mol H2 and 2 mol O2.

  • For 5.8 mol of H2O:

    • Moles of products: Use mole ratios to calculate.

Using Equivalence Statements

• Example Equation:

  • 2H2O = 1O2

• Mole conversion for calculations:

  • If decomposing 5.8 mol of H2O, yield 2.9 mol of O2.

Calculating Required Moles for Reactions

• Example with Propane Reaction:

  • C3H8 + 5O2 → 3CO2 + 4H2O

• Determine moles of O2 needed for 4.30 mol of propane:

  • Relationship: 1 mol C3H8 requires 5 mol O2.