Fundamental Concepts in Chemistry: Matter, Mixtures, and Solubility

Distinguishing Properties and Substances

Explain the differences between the following concepts:

1. Physical vs. Chemical Properties

   Physical properties depend only on the substance itself (e.g., density), whereas chemical properties depend on the interaction with other substances (e.g., reactivity).

2. General vs. Specific Properties

   General properties are not useful for distinguishing types of matter (e.g., mass), while specific properties are useful for identification (e.g., boiling point).

3. Pure Substances vs. Mixtures

   Pure substances have a uniform composition in any of their parts (e.g., water). Mixtures are formed by two or more pure substances combined physically (e.g., saltwater).

4. Simple Substances vs. Compounds

   Simple substances (elements) have only one type of atom (e.g., O₂). Compounds are combinations of two or more simple substances chemically bonded (e.g., H₂O).

Characteristics and Examples of Colloids

Colloids possess distinct characteristics:

• The components of colloids can be distinguished using a microscope.
• They have two parts: the disperse phase and the dispersant phase.

Examples of colloids include milk and blood.

Separation Methods for Mixtures

Different separation techniques are used depending on the mixture type:

Homogeneous Mixture Separation

To separate homogeneous mixtures (solutions), we use methods that involve changes of state (e.g., evaporation to separate water and salt).

Heterogeneous Mixture Separation

To separate heterogeneous mixtures, we use mechanical methods (e.g., filtration to separate water and sand).

Solutions: Definition and Components

A solution is an homogeneous mixture. It has two components:

• Solute: The component present in the smaller proportion.
• Solvent: The component present in the greater proportion.

States of Matter for Solutions

Solutions can be found in all three states (the state of the solution refers to the state of the solvent):

• Solid Solutions

  The most common are alloys: mixtures of metals (we need to melt them first, and then solidify).

• Liquid Solutions

  The most common solvent is water. The solute can be solid (water and salt), liquid (water and alcohol), or gas (soda).

What is Solubility?

Solubility is the maximum quantity of solute that can be dissolved in a fixed quantity of solvent at a certain temperature.

Transforming Diluted to Concentrated Solutions

A diluted solution can be transformed into a concentrated solution by adding more solute.

Effect of Adding Solute to a Saturated Solution

If more solute is added to a saturated solution, the excess solute cannot be dissolved; it will typically precipitate.