Transcript File
Let’s Talk About Evil, Mean, Nasty Water So what was the conversation like between H & O? H + O • H2O is polar – there is an uneven distribution of e-’s • H2O is polar covalent which means it kind of shares e-’s … the e-’s remain mostly with O – H only gets them a small part of the time Like Dissolves Like • If you add a polar substance to a polar liquid, they will mix. • If you add a non-polar substance to a polar liquid, they will not mix. – Ex. Water and oil A little chemistry humor H-bonds Make H2O Stubborn b/c of its molecular structure, H2O is stubborn & will not be broken apart easily; this characteristic is due to H-bonds H-bond – the H from one H2O molecule & the O from another H2O molecule are attracted to each other attraction is weaker than an ionic bond, but it does cause some unique properties Properties of Water • cohesion – attractions between the same molecule – ex: this is why if H2O is spilled it will remain together in a puddle • adhesion – the attraction between molecules of a diff substance – ex: this is why H2O is able to travel up tubes like straws (= capillary action) and the xylem & phloem of plants (= transpiration) • solid form is lighter (less dense) than the liquid form – ex: ice floats • has a high specific heat (specific heat = the amount of E it takes to change 1 g of H2O, 1º) • has a high surface tension – ex: see water glider pic in book H2O is a Snob! • notoriously snobbish, H2O only mixes w/ molecules that are like itself… What molecules are like H2O ? • for ex: when H2O sees NaCl, what does it want to do? NaCl + H2O H2O is the ultimate hater! Putting Stuff Together • mixture (mix) – 2 or more substances combined together but not chemically combined. ex: cereal • solution (soln) – the substances involved are chemically combined. ex: V8 Juice solute = solvent = H2O is the universal solvent! • suspensions – materials that do not dissolve when placed in H2O, but separate into small pieces – ex. Wishbone salad dressing Day 2 WATER LAB Acids & Bases • remember H2O only mixes w/ cmpds that are like itself……who are those cmpds? ____________________________ • H2O is in a constant state of disassociation meaning it goes back & forth btw being a whole molec & ions… hydrogen ion H2O H+ + OHhydroxide ion pH = potential hydrogens pH is a measure of the # or conc of H+ ions in soln… ...THINK about that for a second… the pH scale is based on the power of 10 • Any solution w/ a pH lower than 7 has more hydrogen ions than hydroxide ions in solution. • Any solution with a pH higher than 7 has fewer hydrogen ions than hydroxide ions in solution. • & since the scale is based on the power of 10… a pH of 2 indicates ten times fewer H+ than a pH of 1, pH 3 has ten times fewer H+ than pH 2 & one hundred times fewer H+ than pH 1…… neutral 1 ACIDS = more H+ 7 BASES = more OH14 • acid + H2O H+ + salt ex: HCl + H2O H+ + Cl• base + H2O OH- + salt ex: NaOH + H2O OH- + Na+ Practice Use your knowledge of H2O. If the following substances were dissolved in H2O, would they be considered acids or bases? The answers, and their common names will be revealed on the next slide. 1) HCl 2) H2SO4 3) HNO3 4) H2CO3 5) NaOH 6) Ca(OH)2 7) NH4OH 8) Mg(OH)2 Practice Answers 1) Hydrochloric acid (HCl) in gastric juice 2) Sulphuric acid (H2SO4) 3) Nitric acid (HNO3) 4) Carbonic acid in softdrink (H2CO3) 5) Sodium hydroxide (NaOH) or caustic soda 6) Calcium hydroxide ( Ca(OH)2 ) or limewater 7) Ammonium hydroxide (NH4OH) or ammonia water 8) Magnesium hydroxide ( Mg(OH)2 ) or milk of magnesia Why do we care? • The pH of fluids w/in most cells in the human body must generally be kept btw 6.5 & 7.5. (Is that acidic or basic?) If the pH is higher or lower, it will affect the chem rxns that take place in the cells. • buffers – weak acids or bases that are used to control the acidity or basicity of a substance; they prevent sharp sudden ‘s in pH (remember: = change) PH LAB Checkpoint • What is more acidic? – A solution with a pH of 6 – A solution with a pH of 2 – A solution with a pH of 14 • How do their concentrations of H+ ions compare? Which has more? • What about the OH- ions? So what is a macromolecule? • macromolecules (a.k.a. polymers) - huge organic molecs composed of smaller organic molecs - made up of smaller molecs called monomers - made via a process called polymerization • there are 4 groups of organic cmpds found in living things: (in no particular order) #1 carbs #2 lipids #3 nucleic acids #4 proteins If I were you I would… create a chart that includes the following information: - what the molec does = purpose - what it’s made of = structure - common name - source Carbohydrates • purpose: - E source - plants use it for structure • made of: C, H, & O in a 1:2:1 ratio *simple sugars (monosaccharides) make up complex sugars (polysaccharides)* • common name: • source: Starch Glucose Carbohydrates Lipids • purpose: - store E - parts of membranes - waterproofing • made of: glycerol & fatty acid • common name: • source: LE 5-12a Stearic acid Saturated fat and fatty acid. LE 5-12b Oleic acid cis double bond causes bending Unsaturated fat and fatty acid. Lipids Nucleic Acids • purpose: store & transmit hereditary info • consist of 3 parts: • common name: • source: #1 - 5-C sugar #2 - phosphate group #3 - nitrogenous base Proteins • purpose : - regulate chem rxns (enzymes) - form muscles & bones - transport in & out of cell - fight disease • made of: - amino acids - which have amino (NH2) & carboxyl (COOH) gps • source: Proteins Protein Structure General Structure Amino Group CarboxylG roup Alanine Serine Remember the blue & green sections? Amino acids How You Should Eat Your Macromolecules A Balanced Meal Fiber and the American Diet How to Read a Food Label How to Read a Food Label 2. INGREDIENTS • listed in descending order of weight • required on most foods • sources of some will be stated by name to help people better identify ingredients 3. % of NUTRITION BASE • is a footnote that is on all labels • the % of daily values are based on a 2,000 calorie diet • this is based on current dietary guidance • facilitating the basics of planning a good diet 4. Key Nutrients (+) • choose products with a higher % of daily value from the key nutrients • nutrients with over 10% Daily Value are considered good sources key important nutrients are: •dietary fiber •protein •Vitamin A •calcium •vitamin C •iron Reasons the 6 Key Nutrients* are Good for Your Health • • • • • • protein (5g or more): body cell growth dietary fiber: regulation of digestion vitamin A: night vision vitamin C: healing of tissue iron: health blood calcium: strong bones and teeth nutrients* that relate to health concerns as heart disease, cancer, osteoporosis 5. Excessive Nutrients (-) •over 200 calories is too many •10 % or more of fat, cholesterol, and sodium is excessive • too much can cause health problems • eat in moderation Some of the nutrition slides from this PowerPoint were created by Linda Aldridge Ellision Capital High School 2/4/2000 Types of Rxns • anabolic = produces substance (creates pot E); consumes E ex: monomers put together to make polymers • catabolic = breaks down a substance (creates thermal E); E that was stored becomes available for work ex: like cellular respiration • some chem rxns release E and they often occur spontaneously = exergonic ex: H2 + O2 H2O (can you balance that?) The E is released as heat! • some chem rxns absorb E and won’t occur unless the E is supplied = endergonic ex: the reverse of the above rxn H2O H2 + O2 This rxn will not occur by itself, it requires that much E… activation E – the E needed to get a rxn started Enzymes • catalyst – a substance that speeds up the rate of a chem rxn • enzymes are biological catalysts; they speed up chem rxns that take place in cells; they lower the activation E ex: the rxn used to remove CO2 from the body = CO2 + H2O H2CO3 If left by itself this rxn would take too long & CO2 would build up in the body so there is a specific enzyme (carbonic anhydrase) available to do this job specifically. Activation E Reaction pathway without enzyme Reactants Reaction pathway with enzyme Activation energy without enzyme Activation energy with enzyme Products Can you decipher what these graphs are showing? Energy-Absorbing Reaction Energy-Releasing Reaction products Activation E Activation E reactants reactants products enzymes are very specific! each one will catalyze only 1 chem rxn Look at the video! • http://www.youtube.com/watch?v=XTUm-75PL4&safe=active What can affect enzymes? • denaturation = to alter the original state • changes in pH & temp: even slight changes can denature an enzy = v. dangerous… ...Why?