Glossary
Acids
Substances that donate protons (H⁺ ions) when dissolved in water, increasing the concentration of H⁺ ions.
Example:
Sulfuric acid (H₂SO₄) is a strong acid commonly used in car batteries.
Aqueous Solutions
Solutions in which water acts as the solvent.
Example:
Most reactions in biological systems occur in aqueous solutions, like the cytoplasm within cells.
Bases
Substances that accept protons (H⁺ ions) or produce hydroxide (OH⁻) ions when dissolved in water, increasing the concentration of OH⁻ ions.
Example:
Sodium hydroxide (NaOH) is a strong base used in drain cleaners.
Boiling-Point Elevation
The increase in the boiling point of a solvent when a non-volatile solute is dissolved in it.
Example:
Salting pasta water causes boiling-point elevation, allowing the water to reach a higher temperature before boiling.
Colligative Properties
Physical properties of solutions that depend on the concentration of solute particles, but not on their chemical identity.
Example:
Adding salt to water changes its boiling point and freezing point, which are examples of colligative properties.
Concentration
A measure of the amount of solute dissolved in a given amount of solvent or solution.
Example:
A highly sugary drink has a high concentration of sugar.
Dissociation
The process by which an ionic compound or a molecule breaks apart into its constituent ions when dissolved in a solvent.
Example:
When table salt (NaCl) dissolves in water, it undergoes dissociation into separate Na⁺ and Cl⁻ ions.
Electrolytes
Substances that produce ions when dissolved in a solvent, allowing the resulting solution to conduct electricity.
Example:
Sports drinks contain electrolytes like sodium and potassium ions to help replenish those lost during exercise.
Freezing-Point Depression
The decrease in the freezing point of a solvent when a solute is dissolved in it.
Example:
Spreading salt on icy roads utilizes freezing-point depression to melt the ice by lowering its freezing point.
Homogeneous Mixture
A mixture in which the components are uniformly distributed throughout, appearing as a single phase.
Example:
Air is a homogeneous mixture of gases like nitrogen, oxygen, and argon.
Ions
Atoms or molecules that have gained or lost one or more electrons, resulting in a net electrical charge.
Example:
In an electrolyte solution, the movement of positive and negative ions is responsible for electrical conductivity.
Molality
A measure of concentration defined as the number of moles of solute per kilogram of solvent.
Example:
A solution prepared by dissolving 1 mole of sugar in 1 kg of water has a molality of 1 m.
Nonelectrolytes
Substances that dissolve in a solvent but do not produce ions, and therefore, their solutions do not conduct electricity.
Example:
When sugar dissolves in water, it remains as intact molecules, making it a nonelectrolyte solution.
Raoult's Law
A law stating that the partial vapor pressure of a solvent in a solution is equal to the vapor pressure of the pure solvent multiplied by its mole fraction in the solution.
Example:
Using Raoult's Law, one can calculate the new vapor pressure of water after dissolving a certain amount of glucose.
Solute
The substance that is dissolved in a solvent to form a solution.
Example:
In a cup of coffee, the instant coffee powder is the solute that dissolves in hot water.
Solution
A homogeneous mixture where one substance (solute) is uniformly dispersed in another (solvent).
Example:
When you mix sugar into water, the resulting sweet liquid is a solution.
Solvent
The substance in a solution that dissolves the solute, typically present in the largest amount.
Example:
Water is often called the universal solvent because it can dissolve many different substances.
Strong Electrolytes
Electrolytes that completely dissociate or ionize into ions when dissolved in a solvent, leading to high conductivity.
Example:
Hydrochloric acid (HCl) is a strong electrolyte because it fully breaks apart into H⁺ and Cl⁻ ions in water.
Vapor-Pressure Lowering
The decrease in the vapor pressure of a solvent when a non-volatile solute is added to it.
Example:
Adding sugar to water causes vapor-pressure lowering, meaning fewer water molecules escape into the gas phase above the solution.
Weak Electrolytes
Electrolytes that only partially dissociate or ionize into ions when dissolved in a solvent, resulting in lower conductivity.
Example:
Acetic acid (CH₃COOH), found in vinegar, is a weak electrolyte because only a small fraction of its molecules ionize in water.