Unit+2

=Unit 2 Review Questions=

Separation Techniques

 * When different elements and compounds are mixed together, its not always a good thing.
 * Separate mixtures back into their components
 * elements or compounds separated
 * based upon chemical and physical properties

Density

 * different densities = different layers
 * water more dense than oil and it settles on the bottom of the container, oil layer forms on top, oil can then be suctioned off the layer of the water.
 * less dense=float

Particle Size

 * sifter can be used to separate particles based on size
 * bigger particles remain in the sifter while the smaller particles fall through the holes
 * (filter paper)

Solubility

 * Different compounds are soluble in different solutions
 * Mixing compounds in liquid will create a solution and allow one compound to be rinsed from the unknown
 * Water is often the liquid used for this process
 * (salt and sand) salt will dissolve, sand will not

Boiling and Freezing Points

 * two liquids mixed together- separate either by freezing or heating them
 * if one has a higher freezing point than the other it will freeze and leave the other liquid behind.
 * same with solids- if one has a lower melting point it will begin to melt and leave the other substance as a solid
 * salt water, water can be boiled to get salt back

Charcoal filtration

 * removes color and odor from samples by adding activated charcoal to a sample, then filtering
 * the charcoal collects the extra color and odor
 * filter system in fish tank = charcoal bag

Chromatography

 * Separating tow or more pure, dissolved liquids based on their mass
 * The lighter liquids "climb" a column to be separated
 * ink colors have different masses, lighter inks spread out more

Chlorination

 * Adding chlorine to a substance to kill bacteria

Questions:
How would the process of separation of a mixture of water and salt and water and sand differ? Answer: The mixture of water and salt could be heated to evaporate all water and be left with only salt. If one was trying to only collect pure water distillation would be used to separate water and salt. To separate sand and water, the particle size factor could be used to filter the sand out of the water and let the water drain through.

In our sludge lab, which technique should be used if we wanted to collect pure water? Answer: Distillation because it is the process of evaporating water and catching the water vapor and drip it back into another container, making it possible to collect pure water.