Wednesday, September 30, 2009
Wednes-Day 2
Bio 3,6- we focused on the effect of pH (acidity- low pH or basicity-high pH) on a given enzyme's shape and thus on its rate of activity. We discussed the meaning of pH in terms of concentration of H+ ions in an aqueous solution (e.g. a water mixture like cytoplasm); the greater the concentration of H+, the LOWER the pH, and the more acidic (sour-tasting) the solution.
We saw that each specific enzyme has a particular and narrow "optimal"/best pH range in which it has its proper, natural shape with which it will temporarily bind and catalyze the reaction of its substrate molecule(s). Above or below this pH range, a catalyst will denature/unravel due to the action of too much H+ or too little H+ on the "side groups" of the amino acids that make up the enzyme/protein.
AP Chem- we finished our redox titration analysis problem and determined that commercial hydrogen peroxide is commonly a 3% by mass aqueous solution. We learned that potassium permanganate acts as its own indicator in a titration because it has a deep purple color and it gets reduced to colorless Mn 2+ ion.
We then did two other problem types: one involving "consecutive reaction" stoichiometry, which really proved/showed that coefficients in equations can ONLY and EVER be used to show reaction RATIOS and NEVER the actual quantities that are reacted or produced! In these problems, expect the coefficient to change for the same exact substance in the two different equations because each equation/reaction is independent of the other and the balanced stoichiometric mole ratios of the reactants are likely to be different for different reactions.
We then began a "mixture" problem in which we will use the "weighted average" method to determine the percent composition of each component in the mixture.
We saw that each specific enzyme has a particular and narrow "optimal"/best pH range in which it has its proper, natural shape with which it will temporarily bind and catalyze the reaction of its substrate molecule(s). Above or below this pH range, a catalyst will denature/unravel due to the action of too much H+ or too little H+ on the "side groups" of the amino acids that make up the enzyme/protein.
AP Chem- we finished our redox titration analysis problem and determined that commercial hydrogen peroxide is commonly a 3% by mass aqueous solution. We learned that potassium permanganate acts as its own indicator in a titration because it has a deep purple color and it gets reduced to colorless Mn 2+ ion.
We then did two other problem types: one involving "consecutive reaction" stoichiometry, which really proved/showed that coefficients in equations can ONLY and EVER be used to show reaction RATIOS and NEVER the actual quantities that are reacted or produced! In these problems, expect the coefficient to change for the same exact substance in the two different equations because each equation/reaction is independent of the other and the balanced stoichiometric mole ratios of the reactants are likely to be different for different reactions.
We then began a "mixture" problem in which we will use the "weighted average" method to determine the percent composition of each component in the mixture.
# posted by C @ 5:11 PM 
