Bell Ringer: What 3 things make up a nucleotide? Which macromolecule makes up fats, oils, and waxes? What is the monomer that makes up a protein? What is the polymer that is made up of monosaccharides? Which of the organic compounds are the main source of energy for living things? What is the function of protein?

pH Scale: Acids, Bases, & Water

pH Scale In a solution some water and other molecules tend to ionize Example: H2O  H+ (hydrogen ion) and OH- (hydroxide ion) The concentration of H+ is used to calculate pH The pH scale ranges from 0 - 14

Acids Solution that has a high concentration of H+ ions Chemical formula usually begins with H Has a pH of 6.9 or less Examples: HCl, H2SO4, HNO3, HCH3O3

Acid Examples Hydrochloric acid (HCl) - Strong, found in your stomach that helps to digest your food. Nitric acid (HNO3) - Strong, used in fertilizers Lactic acid - Weak, builds up in your muscles after exercise.

Bases Solution that has a low concentration of H+ (high concentration of OH-) Chemical formula usually ends with OH Has a pH of 7.1 or higher Examples: NaOH, KOH, Mg(OH)2

Base Examples Bleach Soaps Egg White Lye Drano

Buffers Substance that keeps the pH relatively stable when an acid or base is added. Most biological solutions have a natural ability to buffer: blood, milk, saliva, egg white Chemical reactions in living things depend on a stable pH (Homeostasis)

Water Polar Molecule: a molecule that has a positive and a negative side like a magnet. The oxygen atom is at one end and the hydrogen atoms are at the other. Oxygen has a slight negative charge Hydrogen side has a slight positive charge.

Hydrogen Bonds Because of the positive and negative ends, water molecules can attract each other like magnets. Not as strong as ionic or covalent bonds, but they are the strongest bond that can form between two molecules.

Cohesion Cohesion: the attraction between molecules of the same substance. Water molecules LOVE to stick together. Causes molecules on the surface of water to be stuck together. This is called Surface Tension. Why insects can walk on water.

Adhesion Adhesion: an attraction between molecules of different substances. Water molecules are attracted to other substances such as glass. Meniscus in grad. cyl. Capillary action: ability of water to move against the flow of gravity. How plants get water to move from their roots to their leaves.

https://www.youtube.com/watch?v=3jwAGWky98c

+ + - H H O Water Molecule “The Sticky Molecule” E E E E E E E E E E P:1 N:0 H P:1 N:0 E E E E E O P:8 N:8 E E E - E E Water Molecule “The Sticky Molecule”

Questions 1. Why is water polar? 2. What type of bond is happening between the O and H? 3. Which molecule is slightly negative? Why? 4. Which molecule is slightly positive? Why? 5. What type of bond happens between water molecules? 6. a. When a substance has more H+ ions than water, it is a ____ 6. b. When a substance has more OH- ions than water, it is a ___