Chemical Reactions: Energy, Enthalpy, and Reaction Rates
Chemical Reactions and Energy
Compounds or chemicals release stored energy in several ways:
- Thermal Energy (leads to temperature changes)
- Mechanical Energy (movement of objects)
- Electrical Energy (electricity from chemical reactions, like in batteries)
- Light Energy
- Other forms of energy (e.g., sound waves)
Origin of Energy Exchange in Chemical Reactions
Any chemical reaction involves interactions between reacting species that cause bond breaking and formation. Remember:
- Bond Rupture: Requires energy input.
Periodic Table, Atomic Structure, and Chemical Bonding
1. Periodic Table Basics
Key Concepts:
The periodic table arranges elements by increasing atomic number.
Periods (rows) show trends in atomic number and properties.
Groups (columns) have elements with similar chemical properties.
Historical Development:
Mendeleev organized elements by atomic weight and properties.
The modern table uses atomic number for organization.
2. Atomic Structure
Protons: Positive particles in the nucleus.
Neutrons: Neutral particles in the nucleus.
Electrons: Negative particles orbiting
Read MoreChemical Analysis Techniques: Flame Tests, Fingerprinting, Chromatography, and Titrations
Flame Tests
Different elements emit different colors when electric current is passed through them. This is due to the electron configuration within the atom. Chemists use this theory to analyze materials for the presence of certain elements. By observing the emitted colors, they can identify elements in an unknown substance. Traces of different metals are used in fireworks to produce various colors.
We can demonstrate this effect in the laboratory by heating various metal salts in a Bunsen flame.
Read MoreMatter, Atoms, and Electric Charge: A Physics Fundamentals
Mass and Matter
Mass is related to the amount of matter and measures the inertia of a body, exerting gravitational action. A body of 10 kg has twice the inertia of a body of 5 kg. The mass of Jupiter is about 310 times the mass of Earth, resulting in a 310 times larger gravitational force. Density is calculated as mass/volume. The mass of an object measures its inertia, while its weight on Earth is the force drawing it towards the planet.
Material Systems
A material body is any form of matter with
Read MoreMatter: Properties, States, and Mixtures in Chemistry
- Definition of Chemistry
Chemistry is the science of chemical phenomena and the internal structure of matter.
- Definition of Physics
Physics is the science of physical phenomena.
- Physical and Chemical Phenomena
Physical phenomena affect some properties of substances without transforming them into new ones. Chemical phenomena produce new substances with the disappearance of others.
- Definition of Matter
Matter is anything that has mass and occupies a volume.
- Definitions of Mass and Volume. SI Units of Measurement
Mass
Read MoreMixtures and Pure Substances: Properties and Separation
Mixtures and Pure Substances
Definitions
- Homogeneous Mixture: A mixture with components so small they appear uniform to the naked eye. Aqueous solutions are examples of homogeneous mixtures.
- Heterogeneous Mixture: A mixture where the components are visible, either with the naked eye or optical instruments.
- Mixture: Composed of two or more components with undefined proportions.
- Pure Substance: Matter with a definite and constant composition and distinct properties.
- Solution: A homogeneous mixture of two