1 / 30

pH, Acids, Bases, and Buffers

pH, Acids, Bases, and Buffers. Solutions. Solute + Solvent = Solution In nature, water is a major solvent. Concentration – measured in moles Molarity – 1 mol is dissolved in water to equal 1 liter. pH. A measure of the acidity and alkalinity of a solution

tanek
Download Presentation

pH, Acids, Bases, and Buffers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. pH, Acids, Bases, and Buffers

  2. Solutions • Solute + Solvent = Solution • In nature, water is a major solvent. • Concentration – measured in moles • Molarity – 1 mol is dissolved in water to equal 1 liter

  3. pH • A measure of the acidity and alkalinity of a solution • Refers to the dissociation of water molecules. • What does this show?

  4. pH • Constant – Kw = 1.0 x 10-14 (mol/L)2 • i.e. water dissociates at a rate of 1 molecule for every 554 million. • At Kw there is an even split of H+ and OH- • 1.0 x 10-7 each • pH is the negative log of the [H+] in mol/L

  5. pH • Since pH is calculated in log, a change in pH of 1 = a 10x change in the [H+] • pH 1 is 10x smaller than a pH of 2. • pH 1 is 100x smaller than a pH of 3.

  6. Problems • [H+] = 1.0 x 10-9 mol/L. Determine the pH. • [OH-] = 1.0 x 10-9 mol/L. Determine the pH. • Acid precipitation has lowered the pH of a particular lake to 4.0. What is the hydrogen ion concentration of the lake?

  7. Acids and Bases • Acids are molecules that release H+ when dissolved in water. • Ex. Citrus Fruit, HCl • Acids make a solution more acidic. • Bases are molecules that release OH- when dissolved in water. • Lyme, Soap, Ammonia • Make solutions more basic.

  8. Acids and Bases • Neutral pH = 7 • Acidic pH <7 • Basic pH >7 • Most biological fluids are within the range of 6-8 • Blood ~ pH of 7.4 • Exceptions??

  9. Buffers • Substances that minimize changes in the concentrations of H+ and OH- in a solution. • Buffers work by accepting H+ from solution when they are in excess and by donating H+ when they have been depleted. • These buffers are usually composed of a weak acid and its base.

  10. Blood • pH = 7.4 • Humans cannot survive for more than a few minutes if the pH drops to 7 or rises to 7.8 • Buffers in the blood work to maintain the pH at or near 7.4 • Ex. Carbonic Acid

  11. Carbonic Acid • Carbonic acid works with bicarbonate as a buffer. • H2CO3 ↔ HCO3- + H+

  12. Organic Compounds

  13. Organic Compounds • Compounds that contain carbon • Since carbon has 4 valence electrons, it has great versatility. It is able to make 4 covalent bonds. • The major elements of life are C, H, O, N, S, and P

  14. Organic Compounds • Carbon chains form the skeleton of most organic molecules. • Hydrocarbons – consist of only carbon and hydrogen • 3 Types of Isomers • Structural • Geometric • Enantiomers

  15. Structural Isomers • Compounds with the same chemical formula but different structural formulas. • Differ in the covalent arrangement of atoms

  16. Geometric Isomers • Have the same covalent partnerships, but differ in spatial arrangements

  17. Enantiomers • Molecules that are mirror images of each other. • Enantiomers are important in the pharmaceutical industry. • 2 enantiomers of a drug may not be equally effective. From www.elmhurst.edu/~chm/vchembook/209optical.html

  18. Organic Molecules • 4 Types of Organic molecules • Carbohydrates • Lipids • Nucleic Acids • Proteins

  19. Organic Molecules

  20. Carbohydrates • Abbr. – CHO • Composed of C, H, and O • End in “-ose” • Ex. Glucose, Sucrose, Fructose, Starch • 1 CHO = Monosaccharide • CnH2nOn • Glucose = C6H12O6

  21. CHO’s • monosaccharide + monosaccharide  disaccharide + water • This process is called Dehydration Synthesis • Water is removed from the molecules (dehydration) • The two molecules are put together (synthesis)

  22. Monosaccharides Glucose Galactose Fructose Disaccharides Maltose Lactose Sucrose CHO’s

  23. Examples:Sucrose (table sugar) is composed of glucose and fructose.

  24. Polysaccharides • Multiple CHO’s that are put together by dehydration synthesis. • Four important polysaccharides

  25. Lipids • Include fats, oils, waxes, and steroids • All hydrophobic • Consist of 1 glycerol molecule and 3 fatty acids. • 2 types of fats: Saturated and unsaturated • Saturated fats – no C=C double bonds • Unsaturated fats – have C = C double bonds

  26. 1 Glycerol molecule with 3 Fatty Acids Fatty acids are hydrocarbon chains Saturated fats have no double bonds between the carbons that make up the hydrocarbon chain. 1 Glycerol molecule with 3 Fatty Acids Have hydrocarbon chains that do contain at least one carbon-carbon double bond (C=C) Saturated and Unsaturated Fats

More Related