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General Chemistry I: Matter, Measurement, and Problem Solving

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Course Overview

This course, CHEM 161: General Chemistry I, introduces foundational concepts in chemistry, focusing on the study of matter, its properties, and the scientific methods used to investigate chemical phenomena. The course covers chapters 1-11 of the textbook Chemistry: A Molecular Approach by Nivaldo J. Tro.

Course Structure and Requirements

  • Lectures: Tuesdays & Thursdays, 10:30–11:45 am

  • Office Hours: 9:30 am – 4:00 pm

  • Required Materials: Textbook (digital access), scientific calculator

  • Grading: Weekly homework (20%), three exams (20% each), final exam (20%)

Tips for Success

  • Attend lectures and participate in problem-solving activities

  • Work collaboratively and ask questions

  • Clarify concepts before moving on, as chemistry is cumulative

  • Start homework early and practice regularly

  • Take thorough notes during lectures and on handouts

Chapter 1: Matter, Measurement, and Problem Solving

Learning Objectives

  • Describe the scientific approach

  • Classify matter according to its composition

  • Distinguish between chemical and physical properties and changes

  • Compare the Fahrenheit, Celsius, and Kelvin temperature scales

  • Express measurements using appropriate prefix multipliers

  • Apply the density relationship to problems involving mass and volume

  • Determine the number of significant figures in measurements and calculations

  • Convert between units using dimensional analysis

  • Solve problems involving equations

The Scientific Approach

Nature of Scientific Inquiry

The scientific approach is a systematic method for acquiring knowledge about the natural world. It relies on empirical evidence, observation, experimentation, and logical reasoning.

  • Observation: Gathering information using the senses or instruments.

  • Hypothesis: A tentative explanation or interpretation of observations.

  • Experiment: A controlled procedure to test the hypothesis.

  • Law: A concise statement summarizing past observations and predicting future ones (e.g., Law of Conservation of Mass).

  • Theory: A well-substantiated model explaining why nature behaves as it does (e.g., Atomic Theory).

Example: The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction.

Matter and Its Classification

Definition of Matter

Matter is anything that has mass and occupies space. Chemistry studies matter and the changes it undergoes, focusing on atoms, molecules, and their transformations.

Classification by State

  • Solid: Definite shape and volume; particles are closely packed and vibrate in place.

  • Liquid: Definite volume but takes the shape of its container; particles are close but can move past each other.

  • Gas: No definite shape or volume; particles are far apart and move freely. Gases are compressible.

Example: Water exists as ice (solid), liquid water, and steam (gas).

Classification by Composition

  • Pure Substance: Composed of only one type of particle; can be an element or a compound.

  • Mixture: Composed of two or more substances physically combined; can be separated by physical means.

Types of Pure Substances

  • Element: Cannot be broken down into simpler substances by chemical means (e.g., O2, Na).

  • Compound: Composed of two or more elements chemically bonded (e.g., H2O, NaCl).

Types of Mixtures

  • Heterogeneous Mixture: Not uniform throughout; different regions have different properties (e.g., oil and water, salad).

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

Separation of Mixtures

  • Filtration: Separates solids from liquids in heterogeneous mixtures.

  • Distillation: Separates substances based on differences in boiling points.

  • Other Methods: Chromatography, evaporation, etc.

Summary Table: Classification of Matter

Type

Definition

Examples

Element

Pure substance, one type of atom

O2, Na, He

Compound

Pure substance, two or more elements chemically bonded

H2O, NaCl, CO2

Homogeneous Mixture

Uniform composition throughout

Air, saltwater, stainless steel

Heterogeneous Mixture

Non-uniform composition

Oil and water, salad, granite

Chemical and Physical Properties and Changes

Physical Properties and Changes

  • Physical Property: Can be observed without changing the substance's identity (e.g., color, melting point, density).

  • Physical Change: Alters appearance but not composition (e.g., melting, boiling, dissolving).

Chemical Properties and Changes

  • Chemical Property: Describes a substance's ability to undergo chemical changes (e.g., flammability, reactivity with water).

  • Chemical Change (Reaction): Alters the composition of matter (e.g., rusting, combustion).

Example: Burning wood is a chemical change; melting ice is a physical change.

Energy in Chemical and Physical Changes

Types of Energy

  • Kinetic Energy: Energy of motion.

  • Potential Energy: Stored energy due to position or composition.

Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another.

Equation:

Measurement in Chemistry

SI Units and Prefixes

  • Length: meter (m)

  • Mass: kilogram (kg)

  • Time: second (s)

  • Temperature: kelvin (K)

  • Amount of substance: mole (mol)

Common Prefix Multipliers

Prefix

Symbol

Multiplier

kilo

k

103

centi

c

10-2

milli

m

10-3

micro

μ

10-6

nano

n

10-9

Temperature Scales

  • Celsius (°C): Water freezes at 0°C and boils at 100°C.

  • Fahrenheit (°F): Water freezes at 32°F and boils at 212°F.

  • Kelvin (K): Absolute temperature scale; 0 K is absolute zero.

Conversion Formulas:

Significant Figures

  • Definition: Digits in a measurement that are known with certainty plus one estimated digit.

  • Rules:

    • All nonzero digits are significant.

    • Zeros between nonzero digits are significant.

    • Leading zeros are not significant.

    • Trailing zeros are significant only if there is a decimal point.

  • Calculations: The result should have the same number of significant figures as the measurement with the fewest significant figures.

Dimensional Analysis

  • Definition: A method for converting between units using conversion factors.

  • Example: To convert 10 cm to meters:

Density

  • Definition: The ratio of mass to volume.

  • Formula:

  • Units: g/cm3 (solids, liquids), g/L (gases)

  • Application: Used to identify substances and solve problems involving mass and volume.

Summary

  • Chemistry is the study of matter, its properties, and the changes it undergoes.

  • The scientific method is central to chemical inquiry.

  • Matter is classified by state (solid, liquid, gas) and composition (element, compound, mixture).

  • Physical and chemical properties and changes are fundamental concepts.

  • Measurement, significant figures, and unit conversions are essential skills in chemistry.

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