Chemical Calculations and Concepts

Assignment 6 Overview

Due Date

  • Due Date: 10/24/2025

  • Instructions: Write answers on a separate paper. Show all work for full credit.

Problems

  1. Average Atomic Mass Calculation

    • Problem Statement: An element consists of the following isotopes:

      • 1.40% of an isotope with mass 203.973 u

      • 24.10% of an isotope with mass 205.9745 u

      • 22.10% of an isotope with mass 206.9759 u

      • 52.40% of an isotope with mass 207.9766 u

    • Objective: Calculate the average atomic mass and identify the element.

    • Note: u represents atomic mass units (amu).

  2. Chromium Moles and Mass Calculation

    • Problem Statement: Chromium (Cr) is a metal added to steel for corrosion resistance.

    • Given: A sample of chromium containing 5.00 × 10²⁰ atoms.

    • Objectives:

      • Calculate the number of moles in the sample.

      • Calculate the mass of the sample.

  3. Molar Masses of SSRIs

    • Context: Selective serotonin reuptake inhibitors (SSRIs) help to block the reabsorption of serotonin in the brain, boosting mood.

    • Two Medications:

      • Prozac: fluoxetine, C₁₇H₁₈F₃NO

      • Zoloft: sertraline, C₁₇H₁₇Cl₂N

    • Objective: Determine the molar masses of both Prozac and Zoloft.

  4. Ascorbic Acid (Vitamin C) Analysis

    • Chemical Formula: C₆H₈O₆

    • Essentials: It cannot be stored and must be acquired through diet.

    • Objectives:

      • Calculate molar mass of ascorbic acid.

      • Determine the amount (moles) of vitamin C in a typical tablet (500.0 mg) and in 10 tablets.

      • Calculate the number of vitamin C molecules in eight tablets.

  5. Empirical Formula Determination

    • Substance: Dibutyl succinate (roach killer)

    • Composition:

      • 62.58% Carbon (C)

      • 9.63% Hydrogen (H)

      • 27.79% Oxygen (O)

    • Objectives:

      • Determine the empirical formula of dibutyl succinate.

      • Identify additional information needed for molecular formula determination.

  6. Reaction and Product Mass Calculation

    • Reaction Context: Reaction of potassium chlorate with red phosphorus when striking a match.

    • Given: 52.9 g of potassium chlorate (KClO₃) reacting with excess red phosphorus.

    • Objective: Calculate mass of tetraphosphorus decaoxide (P₄O₁₀) produced.

    • Unbalanced Equation:
      KClO<em>3(s)+P</em>4(s)→P<em>4O</em>10(s)+KCl(s)KClO<em>3(s) + P</em>4(s) \rightarrow P<em>4O</em>{10}(s) + KCl(s)

  7. Acrylonitrile Production Calculation

    • Chemical Formula: Acrylonitrile C₃H₃N

    • Overview: Starting material for synthetic carpets and fabrics.

    • Unbalanced Reaction:
      C<em>3H</em>6(g)+NH<em>3(g)+O</em>2(g)→C<em>3H</em>3N(g)+H2O(g)C<em>3H</em>6(g) + NH<em>3(g) + O</em>2(g) \rightarrow C<em>3H</em>3N(g) + H_2O(g)

    • Given:

      • 15.0 g C₃H₆

      • 10.0 g O₂

      • 5.00 g NH₃

    • Objective: Calculate mass of acrylonitrile produced, assuming 100% yield.