Mixtures (2)

IMPURE SUBSTANCES: MIXTURES

PROPERTIES OF MIXTURES

• A mixture is a combination of two or more substances that are not chemically combined

PROPERTIES OF MIXTURES

• No Chemical Changes in a Mixture No chemical changes happen when a mixture is made. So, each substance has the same chemical makeup it had before the mixture was formed.

• Making a mixture is a physical change.

PROPERTIES OF MIXTURES

• Separating Mixtures Through Physical Methods Mixtures can be separated by using physical changes. Physical changes do not change the identities of the substances.

• Some methods could be distillation, evaporation, filtration, dissolve, use of magnets, centrifugation,and chromatography.

PROPERTIES OF MIXTURES• The Ratio of Components

in a Mixture The components of a mixture do not need to be mixed in a definite ratio.

• For example, granite is a mixture of different minerals. Different ratios of the minerals give granite different colors, but the mixture is always called granite.

MIXTURES AND COMPOUNDS

Mixtures Compounds

Made of elements, compounds or both

Made of elements

No change in original properties of the components

Change the original properties of the components

Heat or electricity not required for separating the components

Heat or electricity required for separating the components

Made using any ratio of the components

Made using a fixed ratio of components

TYPES OF MIXTURES

• There are three types of mixtures:

Homogeneous mixtures Colloids

Heterogeneous mixtures

HETEROGENEOUS MIXTURES

• The different components can be seen as individual substances. We can almost separate the components with our eyes.

• The particles are visible (bigger particles)

HOMOGENEOUS MIXTURES• Have the same

composition throughout.• Any one region of the

mixture has the same ratio of substance as any other region

• The components can´t be seen as individual indentifiable entities

• Mixed as much finer level, not readily distinguished

COLLOIDS

• Is a mixture in which the particles are spread throughout but are not large enough to settle out

• The particles are not as small as those of a solution, however are smaller than those of a suspension

COLLOIDS

• Particles in a colloid are large enough to scatter light. A colloid cannot be separated by passing it through a filter.

COLLOIDS• Consists of two separated

phases: Disperse phase (or internal phase) and a continuos phase (or dispersion medium).

• May be solid, liquid or gas

• Some are translucent because of the Tyndall Effect (which is the scattering of light)

Types of colloids

Gas Liquid Solid

Gas None Liquid aerosol Ex: fog, mist, hair spray

Solid aerosol Ex: cloud, smoke, air

Solid Solid foam Ex:aerogel, styrofoam

Gel Ex: jelly, silicagel

Solid sol Ex: cranberry glass

Liquid Foam Ex: whipped cream, shaving cream

Emulsion Ex: milk, mayonnaise, hand cream

Sol Ex: blood

Disperse phase Continuos phase

TYPES OF HOMOGENEOUS MIXTURES

SOLUTIONS (single phase)• A solution is a mixture that

appears to be a single substance. The process in which particles of substances separate and spread evenly throughout a mixture is known as dissolving.

• In a solution, the solute is the substance that is dissolved. The solvent is the substance in which the solute is dissolved.

TYPES OF HOMOGENEOUS MIXTURES

• Examples of Solutions Liquid solutions include soft drinks, gasoline, and tap water. Solutions may also be gases, such as air.

• Solutions may also be solids, such as steel. Alloys are solid solutions of metals or nonmetals dissolved in metals.

SOLUTIONS

• Particles in Solutions The particles in solutions are so small that they never settle out. They also cannot be removed by filtering.

• The particles in solutions are so small that they don’t even scatter light.

SOLUTIONS

Concentrated or Dilute? Solutions can be described as being concentrated or dilute. But these two terms do not tell you the amount of solute that is dissolved.

Concentration= amount of solute

amount of solution

• Solubility is the ability of a solute to dissolve in a solvent at a certain temperature. Depends on the attractions of solute particles for one another and attractions of solvent particles for one another.

• Dissolving Gases in Liquids Gases become less soluble in liquids as the temperature is raised.

• Dissolving Solids Faster in Liquids Three ways to make a solute dissolve faster are mixing the solution, heating the solution, and crushing the solute into smaller particles.

SOLUTIONSUnsaturated solution

A solution that has not reached the limit of solute that will dissolve

Saturated solution A solution in which no more solute can be dissolved

TYPES OF HETEROGENEOUS MIXTURES

• SUSPENSIONS • A suspension is a mixture in

which particles of a material are dispersed throughout a liquid or a gas but are large enough that they settle out.

• The particles in a suspension are large enough to scatter or block light. A suspension can be separated by passing it through a filter.

SUSPENSIONS• Different components are in different

phase, such as solids in liquids or liquids in gases

• It is necessary to shake the substance before using it

HETEROGENEOUS MIXTURES

• You can distinguish the two or more phases.

SOLUTIONS, SUSPENSIONS AND COLLOIDS

Solutions Suspensions Colloids

Uniformly dispersed

More or less dispersed

Intermediate dispersed

Single phase More phases More phases

Small particles Large particles that settle out

Intermediate particles

Can´t scatter light

Scatter or block light

Scatter light