Energy, Thermodynamics, and Thermochemistry Concepts
Energy, Thermodynamics, and Thermochemistry
Energy: The ability of a body or system to produce work or heat transfer. Energy is neither created nor destroyed, only transformed.
Chemical Energy: The energy due to associations between atoms, ions, and molecules that make up each substance. It accumulates in the chemical bonds and joints caused by intermolecular forces.
Work: A mechanism of energy transfer between bodies based on the use of force.
Heat: Thermal energy is transferred naturally or spontaneously
Read MoreAtomic Structure and Chemical Bonds: A Deep Dive
Atomic Structure
- Electron: A very light particle with a negative charge, moving complexly around the nucleus.
- Proton: A particle with a positive charge, equal in magnitude to that of the electron. It is found in the atomic nucleus, and its mass is much higher than that of the electron.
- Neutron: An electrically neutral particle with a mass similar to that of the proton. It is also found inside the atomic nucleus.
Key Concepts in Atomic Structure
- Atomic Number (Z): The number of protons an atom has. Since
Understanding Chemical Bonds: Types, Properties, and Examples
Understanding Chemical Bonds
Link: Union of two or more atoms to form larger entities such as molecules or elements.
Types of Chemical Bonds
Ionic Bond: Union between ions of different signs.
- Occurs when the electronegativity difference is greater than 1.7.
- Typically between a metal and a nonmetal.
- Example: Group IIA + O
Covalent Bond: Forms when the electronegativity difference is not sufficient to transfer electrons from atoms. Atoms share one or more pairs of electrons in an orbital.
Metallic Bond: A
Read MoreWater Treatment Technologies: Membrane Separation, Chlorination, and Activated Sludge
Water Treatment Technologies
Membrane Separation
Membrane separation techniques, such as electrodialysis reversal (EDAR), are used to remove dissolved matter from water, achieving high levels of quality. However, these methods can be expensive, involving semipermeable membranes and dialysis.
Ultrafiltration, a process employing semipermeable membranes, separates contaminants from water under a pressure gradient. It is suitable for macromolecules and industrial effluent treatment.
Reverse Osmosis (RO)
Read MoreUnderstanding Intermolecular Forces, Unit Cells, and Crystal Defects
Intermolecular Forces in Molecular Crystals
Q: What are the various types of intermolecular forces of attraction that hold molecules of molecular crystals together?
A:
- Weak dipole-dipole interactions in polar molecules such as solid HCl, H2O, SO2, etc., which possess a permanent dipole moment.
- Very weak dispersion or London forces in non-polar molecules such as solid CH4, H2, etc. These forces are also involved in monoatomic solids like argon, neon, etc.
- Intermolecular hydrogen bonds in solids such as
Key Concepts and Definitions in Chemistry
- Atom: The smallest unit into which matter can be divided by chemical means.
- Specific Heat: The amount of heat required to raise the temperature of one gram of a substance by 1°C.
- Calorie: The amount of heat needed to raise the temperature of one gram of water by 1°C.
- Science: A systematized set of logical knowledge that relates facts to each other.
- Compound: A homogeneous substance resulting from the chemical union of two or more elements; therefore, it may experience further decomposition.
- Liquid