Polar substances dissolve easily in water, the ‘universal solvent’. The solid state of water (i.e., ice) is less dense than the liquid state, which is why ice floats. Many other substances have to be super-heated or -cooled to change states. Water is the only natural substance that can exist in all three states of matter-solid, liquid, and gas-at the temperatures normally found on Earth. Just like in a magnet, where north poles are attracted to south poles (opposites attract), the positive end of the water molecule will connect with the negative end of other molecules. The other end, with the oxygen, is negatively charged. The end of the molecule with the two H atoms is positively charged. This molecular structure gives the water molecule polarity, or a lopsided electrical charge that attracts other atoms. The two H atoms form weak hydrogen bonds with the oxygen they attach to the top of the molecule rather like Mickey Mouse ears. The way those atoms bond together to form a water molecule is what allows water’s special properties. The chemical composition of water is H 2O-two hydrogen atoms and one oxygen. Water may seem plain and boring sometimes, but it does have some interesting physical properties! Water weighs about 62 pounds per cubic foot at its freezing point it freezes at 0 ☌elsius and boils at 100 ° and it makes up about 60% of the composition of our bodies and 83% of our blood! As for what it can do, water is called the ‘ universal solvent‘ because it can dissolve more substances than any other liquid, even the strongest acid. Acids will turn the pigments in the indicator to a reddish color bases will turn the pigments bluish or yellow-green. You can also make your own pH indicator-use a blender to mix one part chopped red cabbage with two parts boiling water and use the juice to test different solutions. Human blood has an ideal pH of 7.4 even slight fluctuations can seriously affect our bodies. Here are the pH levels of some other substances that you might test: lemon juice (2), vinegar (3), milk (6), egg whites (8), baking soda (9), and ammonia (10). Use the litmus paper to determine which are acids and which are bases. Try testing window cleaner, toilet bowl cleaner, orange juice, and apple juice-pour a little of each into separate test tubes or small glasses or jars. Blue litmus paper turns red when a solution is acidic red litmus paper turns blue in basic solutions. If you have red and blue litmus paper, you can test different solutions for whether they are acids or bases. Litmus is a natural acid-base indicator extracted from a type of lichen. Distilled water is neutral, because the H+ and OH- ions are balanced. Neutral solutions have a pH of 7 and they are neither acidic nor basic. Strong acids have the lowest pH levels (0-4) and strong bases have the highest pH levels (10-14). Acids have a pH below 7 bases have a pH above. The pH scale is used to measure the amount of H+ ions in a solution. Fill the canister with warm water and then quickly put the cap on and watch the acid-base reaction! (An acidic solution is neutralized when a base is added to it, and a basic solution is neutralized by the addition of an acid.)įor another reaction experiment, put an Alka-Seltzer tablet in the bottom of a clear plastic film canister (the kind where the cap fits inside instead of closing over the outside). This releases carbon dioxide gas, which causes the fizzing action in your volcano. You should see an instant eruption! The baking soda, a base, neutralizes the acid in vinegar. To start the eruption, drop a baking soda ‘bomb’ into the bottle-wrap one tablespoon of baking soda into a small piece of tissue paper, tying the ends with thread. Fill the bottle halfway (1 to 1.5 cups) with vinegar. To make a big eruption, use a small plastic bottle (the size 20-oz soft drinks come in works well). One of the simplest activities to show how acids and bases react with each other (and to demonstrate their different properties) is to make a baking soda and vinegar ‘volcano’. The H+ ions in the acid join with and are neutralized by the OH- ions of the base to form H 2O. If hydrochloric acid (HCL) and the base sodium hydroxide (NaOH) are combined, the product is H 2O (water) and NaCl (sodium chloride, a table salt). In many acid-base reactions, the resulting product is water along and a salt. If a solution has a high concentration of OH- ions, then it is basic. If a solution has a high concentration of H+ ions, then it is acidic. Bases, on the other hand, mixed with water yield hydroxide ions (OH-). Hydrogen ions are hydrogen atoms that have lost an electron and now have just a proton, giving them a positive electrical charge. When dissolved in water, acids donate hydrogen ions (H+).
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