Presentation on theme: "Solutions Acids and Bases. Solutions A solution is a mixture in which one or more substances are uniformly distributed in another substance. (Liquids,"— Presentation transcript:
Solutions A solution is a mixture in which one or more substances are uniformly distributed in another substance. (Liquids, gases or solids) The solvent of the solution is the substance in which the solute is dissolved. (Dissolver) The solute of the solution is the substance being dissolved. (Dissolvee) Every solution has a concentration, or the amount of solute dissolved in a fixed amount of the solution. Solutions can become saturated, which means no more of a solute can be dissolved. Aqueous solutions are when water is the solvent.
Dissociation of Water Water molecules are constantly moving. As they move they bump into each other. Sometimes this collision is strong enough to cause a chemical change, where one water loses a hydrogen. H 2 O ↔ H + + OH - The H + is known as a proton. The OH - is known as a hydroxide ion. The free proton joins with a second water and forms H 3 O + which is known as hydronium. H + + H 2 O ↔ H 3 O + Pure water contains equal amounts of OH - and H 3 O + This is why water is neutral.
Acids Acids have a greater number of hydroniums (and therefore H + ) than hydroxides. HCl (Hydrogen Chloride) is a gas. When dissolved in water: HCl ↔ H + + Cl - The free proton can now join with a water to make H 3 O + Most acids have a sour taste, but you should not taste them!!! Ex: lemons, vinegar, rainwater, soda, stomach acid
Bases Bases have a greater number of hydroxides than hydroniums. NaOH (sodium hydroxide) is a solid. When dissolved in water: NaOH ↔ Na + + OH - Alkaline refers to bases. Most bases are bitter tasting, but you should never taste them!!! Ex: Baking soda, Antacids, soaps
pH The pH scale measure the amount of H + in a solution. It runs from 0 – 14 It runs on a log scale. Therefore, the difference between a pH 2 and a pH 3 is 10. We would say that a pH 2 is 10 times more acidic than a pH 3. What about a pH 1 and pH 4? 1000 times
What do the numbers mean? The pH scale measure the amount of H + in a solution. pH X tells us that there is a total of 10 -X M [H + ] in a solution. Ex: pH 5 tells us that there is 10 -5 M [H + ] From pH we can also figure out pOH. pOH measures the amount of OH - in a solution. The sum of pH and pOH should always equal 14. Ex: pH 5 means pOH 9 pOH X tells us that there is a total of 10 -X M [OH - ] in a solution. Ex: pOH 9 tells us that there is 10 -9 M [OH - ]
Buffers This is important because enzymes work in very narrow pH ranges. A buffer is any substance that neutralize an acid or a base. You have natural buffers in your body. Ex: the mucus lining of your stomach buffers the organ from the high acid that is your stomach acid.