Name:___________________________________Date:______________Per:__________
Mixture Separation
Lab 2
Pre-Lab: Mixtures are one-half of the matter picture. Pure substances are the other
half. They are not something that we can separate by physical means. Elements
cannot be separated by ANY means; they are all one thing. Compounds require a
great deal of energy to separate. By contrast, mixtures can easily be separated.
Heterogeneous mixtures can easily be separated; simply pick out the different parts.
Homogenous solutions are more problematic. Solutions can be broken down by
adding something that causes one of the substances to leave solution. Colloids are
handled similarly. Suspensions are easiest of all. Removal of part of the suspension
can be done by passing the mixture (usually something containing water) through
filter paper. The water or other liquid will pass through the tiny spaces in the
barrier but the larger parts of the mixture will not. Water samples with large
particles in it (say, a stream analysis) are often done in this way. We can also isolate
the result of solution separation (called a precipitate) in this fashion and take it for
further analysis if necessary.
Purpose: Learn and practice techniques in removal of a solute from a solution and
for the removal of one component of a suspension by filtration.
Equipment
Test tube
Funnel
Beaker
Copper Sulfate solution
Graduated cylinder
Paper Towel
Ring Stand
Sodium Hydroxide solution
Filter paper
Test tube holder
Ring
Safety
Always wear your goggles when working in the chemistry lab. Handle glassware
with care to avoid breakage that may result in small glass fragments. CuSO4 is a
BIO-HAZARD to sea-life and should never be disposed of down the sink. Dispose of
any extra in the waste bottle indicated. Sodium Hydroxide is a strong base and
burns will occur. Avoid all contact with soft tissues including eyes and mouth.
Procedure
1. Obtain a graduated cylinder, make sure its clear of contaminants and put in
2.0 mL of copper sulfate solution using the provided dropper.
2. Using the dropper given to you, obtain a quantity of acetic acid. Add the
NaOH to the copper sulfate dropwise and record the results.
3. Once no more of the precipitate will form, set the test tube in the holder and
obtain the filter paper and the funnel. Fold the paper as indicated by your
instructor and place it in the funnel.
4. Attach the ring to the ring stand and place the funnel paper in the ring. Place
the beaker under the ring and adjust so that the funnel tip is just below the
lip (and inside) of the beaker.
5. Carefully (to prevent spilling) pour the contents of the test tube into the
funnel. Make sure all of the precipitate leaves the test tube. If some of it will
not come out, squirt a little distilled water into the tube using the squirt
bottle to loosen it and then pour it into the funnel.
6. Allow all of the liquid to drain from the filter paper and then remove. Place
the filter paper on the paper towel and examine the precipitate. Record the
results.
7. Throw the paper towel with the filter paper in it into the trash to dispose.
Dump any remaining liquid into the waste bottle then clean and stow all
glassware.
Observations and Data
Copper Sulfate Solution Observations: ________________________________________
________________________________________________________________________
Copper Sulfate + NaOH Observations: ___________________________________
________________________________________________________________________
Precipitate Observations: __________________________________________________
________________________________________________________________________
Follow-Up
1.
The separation in part 2 is called “gravimetric analysis”. Why do you think
its called that?
2.
How successful was the separation of the suspension through filtration?
Why was that?