CHEM 161: General Chemistry I Study Notes

CHEM 161: General Chemistry I

Course Overview

  • Required Material: Chemistry: A Molecular Approach

  • Access Course Material: Digitally via Lamakū

  • Chapters Covered: 1-11

  • Scientific Calculator Required

  • Grading Breakdown:

    • Weekly Homework assignments: 20%

    • 4 Exams: 20% each (total of 80%)

Access and Resources

  • Lamakū Access: Necessary for Homework assignments (20% of final grade), due every Monday

  • Attendance: Required; early engagement essential for comprehension.

Tips for Success in Chemistry

  • Lecture Attendance: Critical for understanding and engagement.

  • Collaboration: Work in groups, ask each other questions to enhance understanding.

  • Cumulative Learning: Concepts are interconnected; ensure clarity in understanding before progressing.

  • Practice Regularly: Engage with chemistry problems daily to build confidence.

    • Analogy: Learning chemistry is akin to learning a new language.

  • Note Taking: Essential for retention and review of course material.

Additional Resources

  • Learning Assistants (LAs): Available at Learning Emporium, Bilger Addition 209 for science and math tutoring.

  • UH Manoa Learning Center: Offers one-on-one tutoring sessions.

  • Instructor Contact: Office hours available; email inquiries to adelorme@hawaii.edu.

Chapter 1: Matter, Measurement, and Problem Solving

Learning Objectives

  1. Apply the scientific approach.

  2. Classify matter based on composition.

  3. Identify properties and changes in matter as chemical or physical.

  4. Compare Fahrenheit, Celsius, and Kelvin temperature scales.

  5. Express measurements with appropriate prefix multipliers.

  6. Apply the density relationship to mass and volume problems.

  7. Determine significant figures in measurements.

  8. Convert units using dimensional analysis.

  9. Solve problems involving equations.

Definition of Chemistry

  • Chemistry: The study of matter and how it changes, including atoms, molecules, and transformations.

Importance of Chemistry

  • Offers insights into natural systems and phenomena.

The Scientific Approach

Steps in the Scientific Method

  1. Observations: Utilization of senses or instruments for data collection (e.g., sensory characteristics of ʻawa root).

  2. Hypothesis: A provisional explanation of observations (e.g., speculating on the role of compounds in ʻawa).

  3. Testing Hypotheses: Experimentation to validate or disprove hypotheses (e.g., testing solubility and breakdown of compounds in ʻawa).

  4. Hypotheses Must be Falsifiable: Results can support or contradict a hypothesis.

Scientific Laws vs. Scientific Theories

  • Scientific Law: Summarizes observed behavior in nature (e.g., Law of conservation of mass: In chemical reactions, matter is neither created nor destroyed).

  • Scientific Theory: Explanatory model for phenomena (e.g., Theory of Evolution, Theory of Relativity).

    • Law: Describes what happens.

    • Theory: Explains why it happens.

    • Subject to revision based on new evidence; reflects the adaptive nature of scientific understanding.

Atoms and Molecules

  • Atomic Theory: All matter consists of atoms and molecules which determine physical properties.

    • Example: Sodium chloride (NaCl) demonstrates altered properties when forming a compound from its elemental state.

States of Matter

Classification by States:
1. Macroscopic Level:

  • Direct observations such as boiling water.

2. Submicroscopic Level:

  • Microscopic view of matter.

3. Symbolic Level:

  • Chemical representations (e.g., H₂O(l) changes to H₂O(g)).

States of Matter Characteristics:

  • Solid: Fixed volume/shape, incompressible, atoms close together.

  • Liquid: Fixed volume, takes shape of container, incompressible, atoms closely packed yet mobile.

  • Gas: No fixed volume/shape, compressible, atoms widely spaced and mobile.

Classification of Matter

By Composition:

  • Pure Substance: Fixed composition, unique properties; cannot be separated by physical means.

  • Mixture: Combination of two or more substances; can be separated physically.

    • Heterogeneous Mixture: Non-uniform composition (e.g., oil and water).

    • Homogeneous Mixture: Uniform throughout (e.g., air).

Pure Substances Classification:

  • Compounds: Composed of two or more types of atoms bonded chemically (e.g., H₂O).

  • Elements: Composed of one type of atom, cannot be broken down (e.g., O₂, H₂).

Physical vs. Chemical Changes

Definitions:

  • Physical Change: Identity of atoms/molecules remains unchanged (e.g., melting ice).

  • Chemical Change: Alters the composition of matter (e.g., burning wood).

Properties:

Physical Properties:

  • Characteristics that display without changing composition.

    • Examples: Color, state (solid, liquid, gas), boiling point, melting point, density.

Chemical Properties:

  • Characteristics only observable via chemical change.

    • Examples: Flammability, acidity, reactivity with water.

Important Concepts in Problem Solving

Energy Concepts:

  • Energy: Capacity to do work.

  • Work: Force applied through a distance (W=FimesdW = F imes d).

  • Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed.

Measurement Systems:




  • International System of Units (SI):


    Quantity

    Unit Name

    Unit Symbol



    Length

    meter

    m



    Mass

    kilogram

    kg



    Time

    second

    s



    Temperature

    kelvin

    K



    Amount of substance

    mole

    mol



    Electric current

    ampere

    A



    Luminous intensity

    candela

    cd






    Conversion Examples




    • Common conversions and calculations in chemistry.

    • Density (<br>ho=racmV<br>ho = rac{m}{V}), examples with water.

    Significant Figures

    • Reflection of measurement precision. Rules for counting:

      • Non-zero digits: Always significant.

      • Leading zeros: Not significant.

      • Captive zeros: Significant.

      • Trailing zeros with a decimal: Significant.

    • Mathematical Operations:

      • Multiplication/Division: Result should have the same number of significant figures as the measurement with the least significant figures.

      • Addition/Subtraction: Result should reflect the least number of decimal places in the significant figures of the numbers involved.

    Examples of Calculations

    • Provide practice questions to reinforce learning on matter classification, changes, and significant figures, such as identifying which processes involve physical or chemical changes and calculating significant figures in various operations.

    Conclusion

    • Students must complete the 'Why Chemistry?' assignment on Lamakū by January 20 to maintain enrollment. Assessments and engagement in course material are essential for successful outcomes in CHEM 161.