Category Archives: CHE 131

Properties of Matter Part II

Solid to Gas = Sublimination
Gas to Solid = Deposition

The primary difference between states of matter is the molecular structure.

A phase diagram shows how if pressure and temperature is varied, matter will be solid, liquid or gas.

Element + Element = mixture

If a chemical reaction takes place in the mixture it becomes a compound.

Physical properties can be observed without changing. For example: Density, luster, hardness, color, state

Chemial properties can only be observed when the matter is reacting with another substance.

Intensive property: scale invariant (color)
Extensive property: varies w/ amount (mass)

The ratio of 2 extensive quantities that scale in the same manner is an intensive property. ie density = mass/volume.

Measurement and Units:

Accuracy: How close to the true value
Precision: How well can be repeated

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Properties of Matter

First class of Chemistry 131.

There are two types of matter. Mixtures and Pure. The difference between the two is that mixtures can be physically separated, while pure substances can be chemically separated if at all.

Mixtures can be Homo(geneous) or Hetro(geneous). Homo’s are uniform throughout, and Homo’s do not contain the Tyndall effect. The Tyndall effect is the reflection of light off of the small particles suspended in the mixture. For example, it becomes harder to see through fog when the high beams are on. Hetro’s are an uneven distribution of particles, and contains two sub-categories, Colloids and Suspensions. Colloids, which consist of medium size particles and display the Tyndall effect, the particles don’t settle. An example of a colloid is Milk. Suspensions are made from large particles, show the Tyndall effect and the particles settle out. For example, lemonade.

Physical Separation Systems:
Filtration
Distillation
Centrifugation

Pure substances are either Compounds or Elements. Compounds are chemically separable and break down into elements. Compounds contain a fixed ratio of elements. Compounds and elements have a definite make-up (composition?) and properties Compounds are two or more kinds of atom’s that are bonded. (Each element is a type of atom) Mixtures are two or more Compounds.  (Can a mixture consist of two elements as long as it is physically separable?) IE gold and silver beads, mixed together.

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