Lab 5: Acids, Bases, pH

Matter

Anything that has mass and occupies space.

Chemistry

The study of the composition, structure, properties, and changes of matter.

Biological Chemistry (Biochemistry)

The branch of science that explores the chemical processes within and related to living organisms.

Chemical Element

A pure substance that cannot be broken down into simpler substances by chemical means.

Atom

The basic unit of a chemical element, consisting of subatomic particles (protons, neutrons, and electrons).

Atomic Number

The number of protons in the nucleus.

appeaars above the element symbol.

Atomic Mass

The number of protons and neutrons in the nucleus.

appears below the element symbol

Isotopes

atoms that have the same number of protons and a varying number of neutrons

Molecule

the chemical union of two or more atoms

Compounds

molecules composed of different values (i.e. water and chlorophyll)

Chemical Bond

An attraction between atoms, ions, or molecules that enables the formation of chemical compounds.

Electronegativity

A measure of the tendency of an atom to attract a bonding pair of electrons.

Ionic Bond

A chemical bond formed through the electrostatic attraction between oppositely charged ions created by electron transfer.

loss or gain of electrons

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Covalent Bond

A chemical bond formed when two atoms share one or more pairs of electrons.

strong and common in living systems

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally between two atoms with similar electronegativity. (oil)

Polar Covalent Bond

A covalent bond in which electrons are shared unequally due to a difference in electronegativity. (vinegar)

Hydrogen Bond

A weak electrostatic attraction between a positively charged region of a hydrogen atom of a polar covalent molecule and a negatively charged region of oxygen or nitrogen of another polar covalent molecule

Solution

A liquid composed of a uniform mixture of two or more substances.

Solvent

The dissolving medium (water)

Solute

The dissolved substance

Acid

A substance that increases the hydrogen ion (H+) concentration of a solution or donates protons when they dissociate in water.

sour taste

Base (Alkali or Alkalines)

A substance that decreases the hydrogen ion (H+) concentration of their aqueous solution or accepts protons/releases hydroxide ions (OH-) in solution.

bitter taste

pH

A logarithmic measure of the potential hydrogen ion concentration [H+] in an aqueous solution.

measures the acidic or basic nature of a substance

pH Scale

A scale ranging from 0 to 14 used to specify the acidity or basicity of an aqueous solution.

Neutral Solution

A solution with a pH of 7.0, where the concentration of H+ ions equals the concentration of OH- ions.

Acidic Solution

A solution with a pH less than 7.0, containing a higher concentration of H+ ions than OH- ions.

Basic Solution

A solution with a pH greater than 7.0, containing a lower concentration of H+ ions than OH- ions.

pH Paper

Paper treated with chemical indicators that changes color when exposed to an acidic or basic solution.

pH Meter

An electronic device used to measure the pH (acidity or alkalinity) of a liquid precisely.

Red Cabbage Juice Extract

A natural pH indicator derived from red cabbage containing anthocyanin pigments that change color across a wide pH range.

Natural Indicator

A naturally occurring substance (such as anthocyanin) that changes color in response to changes in pH.

Anthocyanin

A water-soluble vacuolar pigment found in red cabbage that acts as a natural pH indicator.

Gastric Juice pH

Approximately 1.5 to 3.5 (Highly Acidic).

Urine pH

Approximately 4.6 to 8.0 (Typically slightly acidic, around 6.0).

Tears pH

Approximately 7.4 (Slightly Basic / Neutral).

Blood pH

Approximately 7.35 to 7.45 (Slightly Basic).

Neutralization Reaction

A chemical reaction between an acid and a base that produces water and a salt, moving the pH toward 7.

Buffer

A solution containing a weak acid and its conjugate base that resists drastic changes in pH when small amounts of acid or base are added.