Intro. To Biochemistry: Water, Solutions and pH

Water…do we need it? Water is 2 Hydrogens & 1 Oxygen H20 Water is POLAR – This means that there is unequal sharing of electrons. Oxygen hogs the electrons and is slightly negative. Hydrogen is slightly positive. HYDROGEN BOND = attraction of water (H2O) molecules to each other Adhesion – tendency of water to stick to different substances Cohesion – tendency of water to stick to itself Surface Tension – the tendency of water to minimize itself & hold together tightly due to uneven pulling by intermolecular forces

Capillary Action Capillary action is the ability of a substance to draw water up against gravity.

Universal Solvent Water is the Universal Solvent. Water has the ability to dissolve other substances Living things are made mostly with water and cannot survive without water

Water Why is water the best solvent: Water is the best solvent because it is polar and pure. Water can dissolve most things. Water is pure but it is also found as part of a mixture. Types of mixtures: Solutions Suspensions

Water Solution: type of mixture where components are uniformly distributed (like sugar water) Solute = what is being dissolved (sugar) Solvent = the thing that is doing the dissolving (water) Suspension: mixture where some components do not dissolve/ remain suspended (muddy lake water)

Acids, Bases, & pH The pH Scale is used to determine the acidity and basicity of substances The pH scale tells us how many H+ ions are in a solution. pH Scale ranges from 0 to 14, 7 is neutral

Acids, Bases, and pH Buffers: weak acids or bases that react with stronger acids/bases to prevent drastic changes in pH Buffers help keep our body’s pH between 6.5 and 7.5 Acid = below 7; the lower the pH the stronger the acid. Acids form H+ ions in solution Neutral = 7 Base = above 7; the higher the pH, the stronger the base. Bases forms OH- ions in solution (alkaline)

Draw a pH scale in your notes