How does isopropyl alcohol differ from water in polarity? Feb 11, To a first approximation, isopropyl alcohol is HALF a water molecule. Explanation: And thus isopropyl alcohol is expected to have some polarity, and SOME water solubility. Related questions Question a. Why are organic compounds important? All of the molecules in the liquid are in constant motion. The warmer the molecules are, the faster they move. When it does, it becomes a gas molecule, and becomes part of the air above the liquid.
Permission Pending Table salt is sodium chloride NaCl. Sodium chloride is an ionic compound, held together by ionic bonds between positively charged sodium ions and negatively charged chlorine ions. The positively charged side of water pulls the chlorine ions away from the salt crystal. The negatively charged side of water pulls the sodium ions away from the salt crystal. You can see this in the image above The green spheres are chlorine; the blue spheres are sodium.
See if you can float a paper clip on the surface of a cup of water. Then see if you can do the same with alcohol. Because water molecules are polar, they connect through hydrogen bonds. They do this at the surface of the body of water where it contacts the air above it , as well inside the body of water.
So try to imagine that paper clip floating on a web of water molecules. The name for this web of water molecules on the surface of a body of water is surface tension. Not that this is not why wood, or aircraft carriers, float on water. Those objects are floating because their overall density is less than that of water mostly because of trapped empty space and air inside the wood or the boat.
The paper clip, by contrast, is much denser than the water. The floating that you observe in the paper clip is caused by surface tension, not by density. Alcohol is much less polar than water. Here are the specific properties of water that you should remember from this lab and video.
Permission pending. If you get the question wrong, it goes back in the deck for you to repeat it. Skip to content. Introduction In the previous tutorial , we looked at the chemistry of water. Does the ink dissolve in the water? What does the solution look like after shaking? Repeat the previous step with cup 4 rubbing alcohol. Does the resulting mixture look different? If so, what is different? Can you explain the differences? Next, pour the alcohol from cup 4 into the water in cup 3.
Put the lid back on and swirl the mixture for five seconds. Does the rubbing alcohol mix with the water? What happens to the color of the mixture? Do you see separate layers forming? Now, add one teaspoon of salt to the mixture in cup 3. Put the lid on the cup and shake it for 20 to 30 seconds.
What happens when you add the salt to the mixture? Does the mixture look different before and after shaking? If so, how does it look different? Can you explain your results? What color is the mixture? Extra: Can you separate other liquid mixtures using salt? What about ethanol and water or acetone and water? Try different liquid mixtures to find out! Extra: Are there any other salts—for example potassium chloride, a salt substitute, or Epsom salt—that you could use to separate liquids?
Repeat the test, but this time use a different salt than table salt. Do you still see the same results? If not—how are your results different? Extra: How much salt do you need to separate the rubbing alcohol and the water? Find out by varying the amounts of salt that you add to the rubbing alcohol and water mixture. Build a Cooler. Make a Potato Shrink--with Saltwater. Get smart. Sign up for our email newsletter. Sign Up. Support science journalism.
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