Matter: Properties and Changes Mixtures What is a mixture? when two or more substances are combined...
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Transcript of Matter: Properties and Changes Mixtures What is a mixture? when two or more substances are combined...
Matter: Properties and ChangesMixtures
What is a mixture? when two or more substances are combined
the individual substances retain their individual chemical properties
most everyday matter exists as mixtures
substances tend to mix naturally
Matter: Properties and ChangesMixtures
a common mixture is the mercury silver mixture in the filling
Although the two substances (mercury and silver) are not distinguishable in this picture, one could separate the mercury from the silver by heating the mixture.
The mercury will boil to a gas before the silver. You would be left with mercury gas and liquid silver, two separate substances.
Matter: Properties and ChangesMixtures
Types of Mixtures -
heterogeneous mixtures - when the individual substances remain distinct, not blending smoothly throughout
example - salad dressings composed of oil, seasonings and vinegar, they will mix but remain distinguishable and if left for long periods of time, will separate out based on density.
Matter: Properties and ChangesMixtures
Types of Mixtures -
homogeneous mixture - mixture that has a constant composition throughout, no one part has more of one substance than another part
these are often referred to as SOLUTIONS
example - most common examples of solutions in daily life are the liquids we are in contact with, like coffee, tea, soda, milk, even tap water
if you take a drink of a soda, the first sip will taste the same as the last, the concentrations of all the chemicals was uniform throughout
Matter: Properties and ChangesMixtures
SOLUTIONS - solutions are not limited to liquids, they can be solids, liquids, gases, or combinations of liquid/gas, solid/liquid, solid/gas
gas/gas - air in a scuba tank composed of nitrogen, oxygen, and argongas/liquid - seawater has oxygen and carbon dioxide dissolved liquid/gas - moist air exhaled by a scuba diver contains water dropletsliquid/liquid - when it rains, fresh water mixes with seawatersolid/liquid - solid salt is dissolved in seawatersolid/solid - the air tank is made of a metal alloy, a mixture of two metals
Matter: Properties and ChangesMixtures
Separating Mixtures - most matter exists naturally as a mixture
in order to understand matter, there was a need to separate the substances from each other using various techniquesFILTRATION - solutions of solid/liquid can be separated using this method
the solution is poured through a filter, trapping the solid while letting the liquid pass through
Matter: Properties and ChangesMixtures
DISTILLATION - this process can be used to separate most solutions
the solution is heated the part of the solution with the lowest
boiling point will phase change firstthe vapor can be directed, collected, and
allowed to condense
Matter: Properties and ChangesMixturesCRYSTALLIZATION - results in the formation of pure solid particles from a solution containing the dissolved substancewhen the solution contains as much dissolved substance as it can hold, the addition of even a little more substance can often cause the substance to come out of solution on any available surface
Matter: Properties and Changes
SUBLIMATION - process by which a solid phase changes into a gas, skipping the liquid phase
can be used to separate 2 solids when one sublimates, while the other does not