Chem Ahmed 1.04 Classification of Matter: Mixtures

What is a mixture:

What is a mixture:

Matter consisting of 2+ kinds of particles physically mixed

Kind of composition in a mixture

Variable

Mixture: ___ may be different, but ___ are always the same

Proportions, components

Mixtures are separated into different components using…

physical changes

What is a heterogeneous mixture?

A non-uniform mixture, not mixed well

Heterogeneous mixture example:

oil and water

2 reasons heterogeneous mixtures have layers:

Different components have different densities, or the components are insoluble

Suspension definition

Heterogeneous mixture that will mix when stirred or shook, but particles will settle at the bottom.

Colloid

heterogeneous mixture that looks homogeneous, but has particles large enough to “hang” in the solution

Homogeneous mixture:

well-mixed, uniform, aka solution, still well-mixed

What constitutes an aqueous mixture?

If things fully dissolve in the mixture

What states of matter can a solution be?

Liquid, solid or gaseous

What is an alloy

solid solution of metals

Characteristics from the alloy-forming process

harder and more durable, soft enough for jewelry making

The Tyndall effect

light is scattered by large particles

Solution definition based on particle dimension

Less than 1 nm in diameter

Can solutions be filtered from solute and solvent?

No

How to separate a solution in (l)

Distillation

Tyndall effect and solutions

Light will not scatter

Interstitial alloy

Comprised of two metals: one metal will have a larger radius than the other. The smaller metal is INTERwoven between the larger atoms.

Substitutional alloy

Comprised of two metals with atoms similar in size. The metals will be arranged as if substituted throughout the mixture.

Interstitial or substitutional?

Substitutional

Interstitial or substitutional?

Interstitial

How to separate components of an alloy (in solid phase)?

Liquation! Melts the alloy until the components reach their melting points

Colloid defined by solute particle diameter

1-1000 nm

Colloids cannot be seen with…

the naked eye

Colloid solutes pass through… but do not pass through…

filter paper; other kinds of paper

Colloids appear … but … and …

cloudy; uniform; homogeneous

Colloid solute particles do not…

sink to the bottom of the container

Colloids and the Tyndall effect

Colloids will scatter light

Emulsions definition

A class of colloid. Either liquid + liquid or liquid + solid, typically liquid + liquid

Stable emulsions require?

an emulsifying agent. EX., oil + vinegar need egg yolk to make mayonnaise

Suspensions defined by solute particle diameter

greater than 1000 nm

Suspensions appear … and …

cloudy and heterogeneous

Can suspension solute particles be filtered?

Yes, they can

Suspensions and the Tyndall effect

Suspensions will scatter light when shaken or stirred. If particles have settled at the bottom, light will not be scattered.

Why can particles be separated in a mixture?

They are not chemically bonded, so they can be physically separated

Filtration

decanting (pouring) through a sieve

Evaporation/boiling

heating on hot plate so that the liquid turns to gas and evaporates

Distillation

Heating the substance in a closed container, evaporating liquid, then cooling and condensing in another container. (only works with different boiling points)

Chromatography

Mobile phase (the mixture) is placed in a stationary fluid. The components travel through the stationary fluid at different speeds, separating them.

Centrifuge

Spinning a mixture at high speeds to separate components of different densities.

Before and after mixing/separating, parts of a mixture

retain their physical and chemical properties