Solutions, Osmosis, Thermodynamics, and Chemical Equilibrium

Vocabulary practice flashcards covering fundamental concepts in solution chemistry, tonicity, concentration calculations, osmolarity, reaction energetics, and Le Châtelier's principle.

Solution

A homogeneous mixture in which solute particles are evenly distributed throughout a solvent.

Solute

The substance dissolved in a solution, such as salt in saltwater.

Solvent

The substance that dissolves the solute, such as water in saltwater.

Aqueous

Dissolved in water; represented as $(aq)$ in a chemical equation.

Concentration

A measurement of the amount of solute present in a specified amount of solution or solvent, depending on the unit.

Dilution

The process of decreasing solution concentration by adding solvent while the amount of solute remains constant.

Osmosis

The net movement of water across a selectively permeable membrane toward the side with a higher concentration of effectively nonpenetrating solute particles.

Osmotic Pressure

The pressure needed to prevent net osmosis across a selectively permeable membrane.

Isotonic Solution

A solution having the same effective concentration of nonpenetrating particles as the cell, resulting in no net water movement and constant cell volume.

Hypotonic Solution

A surrounding solution having a lower effective concentration of nonpenetrating particles than the cell, causing water to enter the cell so that it swells and may burst.

Hypertonic Solution

A surrounding solution having a higher effective concentration of nonpenetrating particles than the cell, causing water to leave the cell so that it shrinks.

Hemolysis

The rupture of red blood cells caused by excessive water entry when placed in a sufficiently hypotonic solution.

Crenation

The shriveling of red blood cells that occurs when water leaves them in a hypertonic solution.

Mass/Volume Percent ($\text{m/v}\%$)

A concentration unit defined as grams of solute per $100\,\text{mL}$ of final solution: $\text{m/v}\% = \left(\frac{\text{grams of solute}}{\text{mL of solution}}\right) \times 100$.

Molarity ($M$)

A concentration unit defined as moles of solute per liter of solution: $M = \frac{\text{moles of solute}}{\text{liters of solution}}$.

Mole

An amount containing approximately $6.022 \times 10^{23}$ specified entities, such as atoms, molecules, or formula units.

Formula Mass

The mass calculated by adding each element's atomic mass multiplied by its number of atoms in the chemical formula, expressed in atomic mass units.

Molar Mass

The mass of one mole of a substance expressed in $\text{g/mol}$, possessing the same numerical value as the substance's formula mass.

Osmolarity

The total concentration of dissolved particles expressed as osmoles per liter of solution ($\text{Osm/L}$), calculated ideally as $\text{molarity} \times \text{number of dissolved particles per formula unit or molecule}$.

Potential Energy

Energy associated with position, arrangement, or interactions; often described as stored energy.

Kinetic Energy

The energy of motion, such as the movement of molecules.

Joule ($\text{J}$)

The SI unit of energy.

Calorie ($\text{cal}$)

A unit of energy approximately equal to the energy required to raise the temperature of $1\,\text{g}$ of water by $1\,^\circ\text{C}$, where $1\,\text{cal} = 4.184\,\text{J}$.

Food Calorie ($\text{Cal}$)

A nutritional energy unit equal to $1\,\text{kcal}$, $1{,}000\,\text{small calories}$, or $4{,}184\,\text{J}$.

Exothermic Reaction

A reaction that releases heat from the system to the surroundings, characterized by a negative enthalpy change ($\Delta H < 0$).

Endothermic Reaction

A reaction that absorbs heat from the surroundings into the system, characterized by a positive enthalpy change ($\Delta H > 0$).

System and Surroundings

The system is the specific chemical reaction being studied, whereas the surroundings encompass everything outside the system.

Enthalpy Change ($\Delta H$)

The heat change of a reaction defined as the difference in enthalpy between products and reactants: $\Delta H = H(\text{products}) - H(\text{reactants})$.

Activation Energy

The energy barrier extending from the reactant energy level to the peak associated with the transition state on a reaction coordinate diagram.

Catalyst

A substance that lowers the activation barrier for both forward and reverse reactions without altering $\Delta H$ or shifting the position of chemical equilibrium.

Reversible Reaction

A reaction capable of proceeding simultaneously in both forward and reverse directions, designated with the symbol $\rightleftharpoons$.

Irreversible Reaction

A reaction that proceeds essentially in only one direction under stated conditions, written using a single forward arrow $\rightarrow$.

Chemical Equilibrium

A dynamic state in which the rates of the forward and reverse reactions are equal, resulting in constant reactant and product concentrations over time.

Le Châtelier’s Principle

The principle stating that when a system at equilibrium experiences a stress, it shifts in the direction that partially counteracts that stress.

Hemoglobin Oxygen-Binding Equilibrium

The physiological equilibrium represented by $\text{Hb} + \text{O}_2 \rightleftharpoons \text{HbO}_2 + \text{heat}$, which shifts right in the oxygen-rich lungs and shifts left in tissues or during fever.