Mixtures and Pure Substances

• Mixtures contain two or more components which each retain their own properties. A pure substance contains only one component, and is made from one type of particle with its own properties.

Heterogeneous Mixtures

• Have easily observable components
• Composition varies within the sample and from one sample to another
• Mixtures with clearly visible components are called mechanical mixtures
• Mechanical mixtures are easy to separate manually

Homogeneous Mixtures

• Also known as solutions
• Their components are difficult or impossible to observe
• The composition is the same throughout the sample

Heterogeneous vs Homogeneous

• Heterogeneous and homogeneous mixtures are classified by their uniformity
• A heterogeneous mixture features parts with different properties and visibility
• A homogeneous mixture exhibits parts that appear the same throughout

Pure Substance vs Solution

• Pure substances always have the same properties due to them being made of the same kind of particle
• Solutions are homogeneous mixtures of two or more substances that combine to form a uniform mixture

Solute vs Solvent

• A solute dissolves
• A solvent is the substance in which the solute dissolves

Concentrated vs Diluted Solutions

• A concentrated solution contains a large mass of dissolving solute for a certain amount of solvent
• A diluted solution contains a small mass of dissolving solute for a certain amount of solvent

Saturated vs Unsaturated Solutions

• A solvent is saturated when it can no longer dissolve solute at the same temperature
• More solute can be added to a unsaturated solution at the same temperature

Solution Examples

• Solid in solid: frying pan, brass door knob, gold ring, concrete
• Liquid in liquid: Mio in water, lemon in tea, apple juice in cranberry juice, vinegar
• Gas in gas: air, natural gas, heliox

Separating Mixtures

• Mechanical sorting separates parts of a heterogenous mixture based on properties
• Heterogeneous mixtures: Filtration, magnetism, and flotation are methods used for separating these mixtures
• Homogeneous mixtures: Evaporation, distillation, and paper chromatography are methods used for separating these mixtures.
• Filtration sorts by particle size.
• Flotation sorts by density.
• Magnetism sorts based on magnetic properties
• Evaporation recovers solid solute from a solution by evaporating liquid solvent
• Distillation recovers the solvent by condensing and collecting gaseous solvent
• Paper chromatography separates based on how fast substances are carried by a solvent through an absorbent material

Simple vs Fractional Distillation

• Simple distillation separates only one solution and one solvent, fractional distillation separates multiple solutes and solvents.
• Fractional distillation is used for complex mixtures, complex mixtures are vaporized and the different parts of the mixture condense at their individual boiling points. Effective for petroleum which has multiple solutes and solvents.

Concentration

• Mass of dissolved solute for a given quantity of solvent
• The amount of solute for a certain quantity of solvent determines the concentration of a solution
• Concentration is commonly measured in grams per litre(g/L)

Solubility

• A soluble substance can dissolve in a given solvent.
• An insoluble substance cannot dissolve in a given solvent
• A substance's solubility can differ based on the solvent used
• Solubility is quantitatively expressed in grams/litre (g/L)

Rate of Dissolving

• Rate of dissolving refers to how quickly a solute dissolves in a solvent
• The rate of dissolving is affected by temperature, stirring and solute size

Separating Liquid Mixtures

• Petroleum is a complex mixture of liquid, solid, and gaseous substances

Separating Solid Mixtures

• All rocks are mixtures; ore is a rock mixture containing a valuable substance like gold or iron
• Gold is denser than rock material, and can be separated based on density, crushing and grinding it with water and other chemicals