In class, my group and I were doing a group experiment. The challenge was to separate these substances understanding their individual properties. The substances we had to separate were sand, salt, bird seeds, and iron filings.
But, how is iron magnetic? Well, we learned in our 5th grade science class that there were two opposite poles that would attract or repel substances. But, that doesn't explain how or why iron is magnetic. I speculate that it has to do with the magnet's chemical and physical properties. Iron may have electrons arranged in a way that will allow it to attract to the magnet. I think it is possible that iron, other magnetic substances, and the magnet itself have similar chemical configurations, which is why they attract to the magnet.
Next, I considered filtering bird seeds since one bird seed is larger than that of a grain of sand or salt. First, though, I needed to know how I was going to separate, but I had to find the why part first since it seemed important to understand more of its properties. I then started thinking about density. I wondered if the density of a bird seed was more or less than that of water. So, I then poured water into a beaker and then put a bird seed in it. It floated. But why? I then started connecting it to its density. The density of bird seed was less than that of water, which is 1 g/mL. Next, I considered possible ways to get the bird seeds out. Since iron is out of the equation, I could pour the rest of the solution into the beaker of water. I figured that since salt and sand stay at the bottom of the sea floor of the ocean or any body of water for that matter, they would sink at the bottom because they have a higher density while the birdseeds would stay afloat. Or, I could use a funnel and fold a coffee filter into it and gradually pour it with water and scoop out the bird seeds until they are completely gone.
However, the main question left is this: How would you separate the sand and the salt when their granule size is so similar? Well, the salt granules are probably smaller than that of the sand. The salt's chemical composition is sodium chloride, while the sand consists of a mixture of minerals. To filter them out, though, it seems the only plausible method is to filter out the sand since its granules seem to be slightly larger. If we found a screener with small enough space to let salt stay in and large enough to get the sand out, then the salt would still be on the screener while the sand would be pored somewhere else through the screen's spaces and then evaporate the water to possibly separate them.
This week, I learned about physical and chemical properties, elements, compounds, and mixtures. First off, physical properties are merely the physical descriptions of an element (e.g. density, solubility, color, melting and boiling points, etc.), while the chemical properties are their chemical descriptions (e.g. flammability, reaction rate, etc.). To review, density is the certain amount of mass (g) in a certain amount of space (mL). It will determine whether a substance will float in any liquid substance. For example, iron will not float into water because it has a greater density, whereas, oil will float on top of water because its density is less than that of water. Next, solubility is the ability to dissolve in any liquid substance. We looked at ethanol and water in class and poured sugar into each. I hypothesized that since ethanol had more viscosity (resistance to flow), it would be harder to dissolve sugar in it. As sugar was poured into both, it took a longer time for sugar to dissolve in ethanol.
I then learned that elements are single pure substances, mixtures were compounds physically mixed together. Compounds were elements chemically mixed together. Take a look at iron and sulfur, for example. If you were to smash the two substances and then physically mix them together, they would just be a mixture of iron and sulfur. Knowing that iron is magnetic and the two substances aren't chemically bonded together, you could separate the iron from the sulfur using a magnet. However, if you put them in a test tube with water and them heat the test tube, they will make iron sulfide. Since these two are chemically bonded, there is no way you could get the iron out using a magnet because the chemical structure is different than the magnet's chemical structure.
It's so interesting to see how your speculations tie in with what you're learning and then connect to other ideas in different experiences you've had. Also, you have the best pictures in your posts.
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