Water Properties & pH Flashcards

Vocabulary practice flashcards covering chemical bonding, unique physical properties of water, solution chemistry, and the pH scale.

Polar Covalent Bond

A chemical bond formed within a single water molecule where electrons are shared unequally between hydrogen and oxygen atoms.

Hydrogen Bond

A weak attraction between a partially positive hydrogen atom of one polar molecule and a partially negative region of another molecule, such as between adjacent water molecules or nucleotide strands in DNA.

Cohesion

The property of water molecules sticking to other like water molecules, which creates surface tension.

Adhesion

The property of water molecules sticking to other, different polar or charged substances or surfaces.

Surface Tension

A property of water resulting from cohesion that allows its surface to resist external force, enabling small organisms like insects to walk across it.

Capillary Action

The process by which water climbs upward against gravity in narrow tubes or cell walls, powered by adhesion sticking to channel walls and cohesion pulling adjacent water molecules.

Specific Heat Capacity

The amount of heat energy required to raise the temperature of a substance by $1\text{ }^\text{o}\text{C}$; water has a high specific heat capacity, absorbing substantial heat with minimal temperature change.

Heat of Vaporization

The amount of heat energy needed to convert liquid water into a gas, which allows evaporative cooling mechanisms like sweating to lower body temperature.

Solvent

The liquid component of a solution that dissolves a solute.

Solute

The chemical compound or substance that is dissolved into a solvent.

Solution

A homogeneous liquid mixture composed of a solute dissolved uniformly within a solvent.

Hydrophilic

Having an affinity for water; describing polar or charged molecules that dissolve easily in water.

Hydrophobic

Lacking an affinity for water; describing nonpolar molecules that do not dissolve in water.

pH

A quantitative logarithmic measure of hydrogen ion concentration $\text{[H}^+\text{]}$ in a solution, calculated as $\text{pH} = -\text{log}\text{[H}^+\text{]}$.

Hydrogen Ion $\text{(H}^+\text{)}$

A positively charged single proton formed when a hydrogen atom loses its sole electron.

Hydroxide Ion $\text{(OH}^-\text{)}$

A negatively charged ion created when a water molecule dissociates and the oxygen atom retains the electron from a hydrogen atom.

Acid

A compound that releases hydrogen ions $\text{(H}^+\text{)}$ into an aqueous solution, increasing $\text{[H}^+\text{]}$ and yielding a $\text{pH}$ value below $7$.

Base

A compound that releases hydroxide ions $\text{(OH}^-\text{)}$ in water or accepts hydrogen ions, decreasing $\text{[H}^+\text{]}$ and yielding a $\text{pH}$ value above $7$.

Buffer Systems

Chemical solutions and cellular mechanisms that stabilize internal $\text{pH}$ by absorbing or releasing hydrogen ions to protect protein and membrane function.

Molecular Structure of Water States

The arrangement of water molecules across states of matter: highly ordered in frozen ice, semi-ordered in liquid water, and random in vaporized gas.

Polar Covalent Bond

A chemical bond within a single water ($H_2O$) molecule formed by the unequal sharing of electrons between oxygen and hydrogen.

Hydrogen Bond

A weak attraction formed between different water molecules or holding together the two long chains of nucleotides in $DNA$.

Cohesion

The property where molecules stick to like molecules, such as water molecules sticking to each other to create surface tension.

Adhesion

The property where molecules stick to other substances, such as water molecules clinging to plant cell walls or glass surfaces.

Capillary Action

The movement of water upward through narrow spaces against gravity, driven by adhesion and cohesion, allowing plants and trees to absorb water.

Surface Tension

A measure of the difficulty in breaking the surface of a liquid, produced by cohesive hydrogen bonding among water molecules that allows insects to walk across water.

Specific Heat Capacity

The amount of heat energy needed to increase the temperature of a substance by $1^\text{o}\text{C}$; water has a high specific heat capacity and absorbs substantial heat without large temperature shifts.

Heat of Vaporization

The amount of energy required to convert liquid water into a gas; water's high heat of vaporization removes heat energy and cools organisms during sweating.

Density of Ice

The physical property that solid water is less dense than liquid water because stable hydrogen bonds keep ice molecules held farther apart, allowing ice to float.

Solvent

The liquid substance in a solution in which another compound is dissolved.

Solute

The compound or chemical substance that is dissolved into a liquid solvent.

Solution

A liquid mixture formed when one or more solutes dissolve completely in a solvent.

Hydrophilic

Describing molecules or substances that have an affinity for water and dissolve easily in aqueous solutions.

Hydrophobic

Describing molecules or substances that repel water and do not dissolve easily in aqueous solutions.

pH

A quantitative logarithmic measure of hydrogen ion concentration in a solution, defined mathematically as $\text{pH} = -\text{log}[H^+]$.

Hydrogen Ion ($H^+$)

A single positively charged proton formed when a hydrogen atom loses its lone electron.

Hydroxide Ion ($OH^-$)

A negatively charged ion formed when a water molecule dissociates and the oxygen atom retains the shared electron from hydrogen.

Acid

A compound that releases hydrogen ions ($H^+$) in water, resulting in a higher $[H^+]$ and a lower $\text{pH}$ value between $1$ and $6$.

Base

A compound that releases hydroxide ions ($OH^-$) in water, resulting in a lower $[H^+]$ and a higher $\text{pH}$ value between $8$ and $14$.

Buffer Systems

Biological mechanisms and solutions that prevent sharp changes in $\text{pH}$ inside organisms to maintain homeostasis and preserve protein structure and membrane function.

Xylem

Plant vascular tissue inside which water molecules use adhesion to stick to the cell wall and cohesion to stick to each other during upward transport.