Mixtures 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
Food Dehydration: Methods, Principles, and Moisture Analysis
Dehydration for Food Preservation
Dehydration reduces food’s water content to less than 13%. Advantages include excellent protection against spoilage as microorganisms cannot develop without water, enzymatic activity is inhibited, and chemical reactions slow down. Dehydration is optimal for products stored at elevated temperatures. To achieve maximum protection, remove virtually all water and store the food in tightly sealed containers, isolated from oxygen, light, insects, and rodents. Freeze-drying,
Read MoreUnderstanding Fire: Combustion, Classification, and Extinguishing Methods
Triangle of Fire
Combustion requires three elements: a substance that is oxidized, a substance that is reduced, and energy (activation energy, usually heat) to initiate the reaction. If any of these elements is missing, combustion will not occur.
Oxidant: Oxygen is the primary oxidizer in most combustion processes.
Fuel: Any substance capable of undergoing combustion or combining with oxygen to produce an exothermic reaction.
Heat: Energy required to start the reaction, often provided by ignition sources
Read MoreUnderstanding Atoms, Molecules, and States of Matter
Atom
The matter consists of atoms. These consist of the nucleus and cortex. The core is formed by protons (p+) and neutrons (n). The crust consists of electrons (e–).
Ions
An atom can become an ion by electron gain or loss. If it gains electrons, it becomes an anion (negatively charged ion). If it loses electrons, it produces a cation (positively charged ion).
Atomic Number (Z)
The atomic number is the number of protons in the nucleus of an atom. It identifies the atoms of an element. This matches the
Read MoreUnderstanding Amino Acid Properties and Protein Structure
Amphoteric Character
Amino acids possess an amphoteric character due to the presence of both carboxyl and amino groups. The carboxyl group can lose a proton, acting as an acid, while the amino group can accept a proton, acting as a base. This dual behavior allows amino acids to act as both acids and bases depending on the pH of the environment. The side chain may also contain ionizable groups, further influencing the amino acid’s charge.
Isoelectric Point
The isoelectric point (pI) is the pH at which
Read MoreAmino Acids: Building Blocks of Proteins
Amino Acids: The Monomers of Proteins
Amino acids are the building blocks of peptides and proteins. Over twenty amino acids are found in proteins and are common to all living organisms.
Molecular Structure
All protein amino acids share a common structure: an amino group (-NH2), which is basic, and a carboxyl group (-COOH), which is acidic. They also have a unique side chain (R group) that varies among different amino acids.
Classification of Amino Acids
Amino acids are classified into four groups based
Read More