Understanding Substances, Mixtures, and Separation Techniques

Substances, Mixtures, and Separation Techniques

1. Pure Substances vs. Mixtures

• Distilled Water: Pure substance/compound
• Tap Water: Mixture/homogeneous
• Diamond: Pure substance/element
• Gasoline: Mixture/homogeneous
• Wine: Mixture/homogeneous
• Air: Mixture/homogeneous

2. Dalton's Theory

• Matter is made up of indivisible and indestructible atoms.
• All atoms of the same element are equal in mass and properties.
• Compounds are formed by the combination of different elements.

3. Separation Techniques

• Screening: Separates solid particles of different sizes. Instrument: sieve.
• Filtration: Separates solids from liquids. Instrument: filter.
• Evaporation: Separates solids from liquids when the liquid is not needed. Works best with homogeneous mixtures. The process is faster when heated.
• Settling: Separates immiscible mixtures based on density. Used for heterogeneous mixtures.
• Magnetic Separation: Separates ferromagnetic materials using a magnet.
• Distillation: Separates immiscible liquids or components of a solution by exploiting differences in boiling points.

4. Separating Sand, Gasoline, and Iron

1. Use a magnet to separate iron filings from gasoline and sand. The iron filings will stick to the magnet.
2. Pour the gasoline and sand mixture into a filter. The gasoline will pass through, leaving the sand on the filter paper.

5. Dissolution and Components

Physiological serum is a homogeneous mixture with distinguishable components. It is a liquid solution where the solvent (water) is in greater proportion and the solute (salt) is in lesser proportion.

6. Dissolution Based on Solute Quantity

• Dilute Solution: Little solute relative to the solvent.
• Concentrated Solution: Plenty of solute relative to the solvent.
• Saturated Solution: Maximum amount of solute dissolved in the solvent.
• Supersaturated Solution: More solute than normally possible, often achieved by heating.

7. Formulas

• % by mass of solute = (mass of solute / mass of solution) x 100
• % by volume of solute = (volume of solute / volume of solution) x 100
• Mass concentration of solute = mass of solute / volume of solution
• Solubility = g solute / 100 mL solvent = g solute / L solvent

1 g = 1000 mg

1 L = 1000 mL