Understanding Acids, Bases, and pH (Part 3)

The pH scale measures solution acidity or alkalinity based on hydrogen ion concentration.

Highlight: A single pH unit change represents a tenfold difference in hydrogen ion concentration.

Example: A pH of 1 is 1000 times more acidic than a pH of 4.

Acids and bases have distinct properties that affect biological systems.

Definition: Buffers are substances that help maintain stable pH levels by accepting or donating hydrogen ions as needed.

Highlight: Living cells maintain internal pH close to 7 through buffer systems.

Example: Common acids include citrus juices and gastric acid, while bases include soap and bleach.

Water's Essential Properties (Part 1)

Water's molecular structure and chemical properties make it fundamental for life. The H₂O molecule forms through covalent bonds and exhibits polarity due to uneven electron distribution between oxygen and hydrogen atoms.

Definition: Polar molecules have an uneven distribution of electrical charge, with one end being positive and the other negative.

Highlight: Hydrogen bonds, though weaker than covalent bonds, are crucial for water's unique properties.

The first key property is capillary action, resulting from water's cohesive and adhesive properties.

Vocabulary: Cohesion refers to water molecules sticking together, while adhesion describes water's ability to stick to other substances.

Example: Capillary action enables water transport in plant vessels and drinking straws.

Surface tension, another vital property, makes it difficult to break water's surface.

Highlight: Water's high specific heat helps maintain stable environmental temperatures, as demonstrated in pond ecosystems.