This is my twelth science project. It is about separating molecules.

Objectives:

Explore different ways of separating mixtures of large, dissimilar objects.

Explore different ways of separating mixtures of small, similar objects.

Use chromatography to separate molecules from mixtures.

Predictions:

If I had rocks and lego parts mixed together, I would separate them by sorting the lego parts and the rocks into two groups by them out and putting them in piles with my hands.

If I had rocks and sand together in a bag, I would separate them by dump them in a shifter and collect the sand with a bowl and the rocks in a pile.

If I had sand and salt together in a bag, I would separate them by dumping them in a shifter and collecting the sand and salt in separate bowls.

If I had salt and sugar together in a bag, I would separate them by dumping them in a shifter and collecting the salt and sugar in separate bowls.

If I had salt and sugar together in water, I would separate them by evaporating the water, then dumping the salt and sugar in a shifter and collecting the salt and sugar in separate bowls.

Observations:

Separating Lego parts from big and small rocks.

I dumped the rocks and the Lego pieces out of their bag in which they were mixed onto a tray and separated them with my hands. This procedure would not work with a huge pile of Lego pieces and rocks. In fact, there is no good way to separate a huge pile of Lego pieces and rocks with one person alone.

Separating rocks from sand.

I dumped the rocks and sand out of their bag in which they were mixed into a colander and the sand came out bottom while the rocks stayed inside the colander. This would work for large quantities too.

Separating sand from salt.

I dumped the sand and salt out of their bag in which they were mixed into a bottle which I filled with water. The salt dissolved into the water, leaving the sand behind. I dumped the water out and the sand was left on the bottom.

Separating salt from natural sugar.

I talked to Sarah about it and we decided that ants would be the candidates for the test,  but we couldn’t find any. Deciding to see what would happen if I poured it into water, I dumped the salt and natural sugar out of their bag in which they were mixed and into a bottle of cold water. The natural sugar sank to bottom and did not dissolve, while the salt was dissolved nearly instantly. I found it very surprising 

A chromatography experiment.

I put green, blue, yellow, and red food coloring in a jar with a strip of coffee filter hanging down from a chopstick. The blue started up the filter first, followed by the green, then the yellow, and finally the red. Unfortunately, the blue, green, and yellow mixed together into a greenish mess and nobody could tell which was which.  

Sarah and I independently made “Mystery Liquids” by combining a couple of food colors and water in a jar.  Using chromatography, we each tried to discover the other person’s food coloring liquids. Sarah’s prepared colors were yellow and blue and my prepared colors were blue and red.

Sarah’s liquid was a challenge to determine the colors. On the strip, I saw a little line of blue and the rest was green.  The liquid was green. It couldn’t have red in it, that was clear. So my choices were limited to blue, green, and yellow. I guessed that the colors Sarah added were yellow and green. That guess was wrong. Because blue and yellow can make green, I then correctly guessed blue and yellow. 

The chromatography strip did a good job separating the colors for Sarah, allowing her to guess correctly on her first try.

We put blue and green in a jar and the test strip came out with a little bit of blue at the top and the rest being green. 

We put yellow and green in a jar and the test strip came out with a line of bluish color and the rest being yellowish green.

We put yellow and red in a jar and the test strip came out with a section of faint yellow and a section of red.

Results:

We discovered four ways to un-mix things.

1. Pick them apart by hand.

2. Dump them into a colander.

3. Dissolve them.

4. Chromatography them.

I can un-mix the rocks from the Lego parts with my hands, but not with water or chromatography, because the Lego parts are big enough to un-mix by hand, the water would only flood them, and they aren’t colors.

I can’t un-mix the sand from the rocks using my hands, water, or chromatography, because I can’t pick up sand, the water would push the sand over everything, and they aren’t colors. I could use a colander with my hands to separate the rocks and sand though.

I can un-mix the sand from the salt with water, but not with my hands or chromatography, because the water dissolves the salt and leaves the sand, the grains are too small to pick up with my hands, and they aren’t colors.

I can un-mix the salt from the sugar using water, but not with my hands or chromatography, because the water dissolves the salt and leaves the sugar, the grains are too small to pick up with my hands, and they aren’t colors.

I can un-mix the colors with chromatography, but not with my hands or water,

because chromatography splits the colors, I can’t pick up colors, and water would only dilute the colors. 

Conclusion:

Large, dissimilar things are easier to separate than small, similar things. Large things are easier to pick up with your hands than small things. Dissimilar things are easier to separate because it is easier to spot differences in dissimilar things than in similar things with your eyes. 

Small similar objects are harder to sort unless there is an important difference, like dissolving in water. The salt, sugar, and sand all are the same size, except the salt dissolves in water and the salt and sugar don’t. This made it easy to separate the salt, sugar, and sand.

For chromatography to work, you need unique molecules, but you don’t have to see that difference. The green food coloring didn’t separate from the blue and yellow food coloring because it was formed from the blue and yellow food coloring. The red food coloring separated from the yellow and blue food coloring because it was a unique and a dark color.