Transcript Water
WATER WATER • THE MOST ABUNDANT COMPOUND ON EARTH • COVERS 75% OF EARTH • 98% LIQUID WATER • 2% ICE • CONSIDERED THE “UNIVERSAL SOLVENT” • ONE OF THE ESSENTIAL NUTRIENTS NUTRIENTS NUTRIENTS: FOOD COMPONENTS NECESSARY TO SUSTAIN LIFE THE SIX ESSENTIAL NUTRIENTS INCLUDE: 1. WATER 4. PROTEINS 2. CARBOHYDRATES 5. VITAMINS 3. FAT 6. MINERALS STRUCTURE OF WATER • CHEMICALLY COMPOSED OF TWO HYDROGEN ATOMS AND ONE OXYGEN ATOM • THE MOLECULAR FORMULA FOR WATER IS H2O • RESULT OF COVALENT BONDS COVALENT BONDS • CONNECTS THE HYDROGEN TO THE OXYGEN • ELECTRONS CAN BE SHARED EQUALLY OR UNEQUALLY BETWEEN ATOMS • WHEN ELECTRONS ARE SHARED EQUALLY: • ELECTRONS SPEND THE SAME AMOUNT OF TIME ORBITING THE NUCLEUS OF EACH ATOM • THE OPPOSITE CHARGES BALANCE OR NEUTRALIZE EACH OTHER • THE MOLECULE DOES NOT HAVE AN ELECTRICAL CHARGE • CREATES NONPOLAR COVALENT BONDS: BOND IN WHICH THE ELECTRONS ARE SHARED EQUALLY AND THE OPPOSITE CHARGES BALANCE EACH OTHER COVALENT BONDS • WHEN ELECTRONS ARE SHARED EQUALLY: 1. The electrons of two hydrogen atoms repel or push away from each other 3. The protons of one atom attracts the electrons of another atom. The outer orbital prefers to have two electrons. 2. The protons of two hydrogen atoms also repel each other. 4. In covalent bonds, each electron travels in the orbitals around both nuclei. COVALENT BONDS • WHEN ELECTRONS ARE SHARED UNEQUALLY: • WATER MOLECULE FORMS A V SHAPE • LARGER OXYGEN NUCLEUS PULLS THE SHARED ELECTRON TOWARD THE OXYGEN ATOM MORE FREQUENTLY • DEVELOPS REGIONS OF OPPOSITE ELECTRICAL CHARGES • HYDROGEN IS SLIGHTLY POSITIVE AND OXYGEN IS SLIGHTLY NEGATIVE • CREATES POLAR COVALENT BOND: BOND WITHIN A MOLECULE IN WHICH THERE IS AN UNEQUAL SHARING OF ELECTRONS HYDROGEN BONDS • BONDS BETWEEN WATER MOLECULES • LIKE CHARGES WILL REPEL EACH OTHER WHILE OPPOSITE CHARGES WILL ATTRACT • HYDROGEN BONDS: ATTRACTION OF A POSITIVE HYDROGEN END OF ONE WATER MOLECULE TO THE NEGATIVE OXYGEN END OF OTHER WATER MOLECULES • HYDROGEN BONDS ARE INTERMOLECULAR: BETWEEN MOLECULES • INTERMOLECULAR BONDS ARE MUCH WEAKER THAN COVALENT BONDS • HYDROGEN BONDS CAN OCCUR BETWEEN WATER AND OTHER POLAR MOLECULES • FOODS THAT COMMONLY FORM HYDROGEN BONDS: SUGARS, STARCHES, AND PROTEINS HYDROGEN BONDS SURFACE TENSION • SURFACE TENSION: FORCE BETWEEN MOLECULES AT THE OUTSIDE EDGE OF A SUBSTANCE • HYDROGEN BONDS GIVE WATER GREATER SURFACE TENSION THAN MOST COMPOUNDS • ALLOWS LIQUIDS SURFACE TO RESIST EXTERNAL FORCE (OVERFILL GLASS OF WATER W/O SPILLING) • WATER IS BOTH COHESIVE – ABILITY TO CLING TO ITSELF – AND ADHESIVE – ABILITY TO CLING TO SOMETHING ELSE AS WELL AS ITSELF • MENISCUS FORMS BECAUSE THE ADHESION BETWEEN WATER AND THE CONTAINER IS STRONGER THAN THE COHESION AMONG WATER MOLECULES SURFACE TENSION • INCREASED SURFACE TENSION RESULTS IN HIGHER MELTING AND BOILING POINTS • REQUIRES MORE ENERGY FOR POLAR MOLECULES TO MELT/BOIL • WATER MOLECULES HAVE MORE SPACE BETWEEN THEM WHEN FROZEN THAN IN LIQUID FORM • LIKE CHARGES ARE REPELLING ONE ANOTHER • TINY MICROSCOPIC HOLES IN ICE • ICE BECOMES LESS DENSE THAN WATER PRESSURE, TEMPERATURE, AND PHASE CHANGES • ATMOSPHERIC PRESSURE (ATM): THE FORCE OF WEIGHT OF GASES IN THE AIR PRESSING DOWN ON A SURFACE • BASED ON THE AVERAGE PRESSURE OF THE ATMOSPHERE ON AN OBJECT AT SEA LEVEL • =1.0 ATM OR 14.7 POUNDS PER SQUARE INCH PRESSURE, TEMPERATURE, AND PHASE CHANGES • AS ALTITUDE INCREASES, THERE IS LESS ATMOSPHERIC PRESSURE • DENVER, COLORADO IS 1 MILE ABOVE SEA LEVEL, AVERAGE PRESSURE IS 0.83 ATM • AT LOCATIONS BELOW SEA LEVEL, ATMOSPHERIC PRESSURE INCREASES • DEATH VALLEY HAS AN AVERAGE PRESSURE OF 1.01 ATM PRESSURE, TEMPERATURE, AND PHASE CHANGES • LESS ATMOSPHERIC PRESSURE REQUIRES LESS ENERGY TO CHANGE PHASES • HIGH ALTITUDES WHERE ATMOSPHERIC PRESSURE IS LOW, WATER WILL BOIL AT LOWER TEMPERATURES • MT MCKINLEY (20,320 FT ABOVE SEA LEVEL), WATER BOILS AT 78 DEGREES CELSIUS • LOW ALTITUDES WHERE ATMOSPHERIC PRESSURE IS HIGHER, WATER WILL BOIL AT HIGHER TEMPERATURES • DEAD SEA (1,286 FT BELOW SEA LEVEL), WATER BOILS AT 101 DEGREES CELSIUS FUNCTIONS OF WATER IN FOOD PREPARATION WHAT ARE SOME DIFFERENT WAYS THAT WATER IS USED IN FOOD PREPARATION? FUNCTIONS OF WATER IN FOOD PREPARATION 1. MEDIUM FOR TRANSFERRING HEAT • FOOD IN WATER HAS LITTLE EFFECT ON THE BOILING POINT OF WATER • GENTLY BOILING WATER HAS THE SAME TEMPERATURE AS RAPIDLY BOILING WATER • SOME FOODS NEED RAPID BOIL • PASTA – KEEPS PASTA MOVING TO PREVENT IT FROM STICKING TOGETHER • OTHERS NEED A GENTLE BOIL • ALLOWS FOR A SLOWER RATE OF HEAT ABSORPTION TO PROMOTE EVEN COOKING • EX: POTATOES FUNCTIONS OF WATER IN FOOD PREPARATION 1. MEDIUM FOR TRANSFERRING HEAT • IF NOT UNDER PRESSURE, STEAM AND BOILING WATER WILL HAVE THE SAME TEMPERATURE • LATENT HEAT: THE ENERGY REQUIRED TO CAUSE A PHASE CHANGE WITHOUT A CHANGE IN TEMPERATURE • STEAM WILL TAKE SLIGHTLY LONGER TO COOK FOODS THAN BOILING WATER • IF PRESSURE IS ADDED, STEAM CAN COOK FOODS FASTER • BOILING POINT INCREASES UNDER PRESSURE • ADVANTAGES OF STEAM COOKING: MORE FLAVORFUL AND MORE NUTRITIOUS FUNCTIONS OF WATER IN FOOD PREPARATION 1. MEDIUM FOR TRANSFERRING HEAT • STEAM CAN ALSO ACT AS A LEAVENING AGENT IN BAKED GOODS • WATER EXPANDS AS BATTER/DOUGH IS HEATED • SMALL POCKETS OF STEAM CREATE CELLS • EX: POPOVERS ARE MADE FROM A THIN BATTER COOKED AT HIGH TEMPERATURES FUNCTIONS OF WATER IN FOOD PREPARATION 2. NECESSARY INGREDIENT FOR FORMING MANY FOOD MIXTURES • GAS-IN-WATER SOLUTIONS • CARBONATED BEVERAGES – 1ST CREATED WHEN WATER PASSED THROUGH LIMESTONE UNDER PRESSURE • OXYGEN IN WATER – BOIL WATER TO REMOVE DISSOLVED OXYGEN • LIQUID-IN-WATER SOLUTIONS • MOST ALCOHOLIC BEVERAGES • VINEGAR IN WATER FOR PRESERVING PICKLED FOODS • SOLIDS-IN-WATER SOLUTIONS • SALT AND SUGAR MOST COMMON SOLIDS • CAUSE WATER TO FREEZE AT LOWER TEMPERATURES AND BOILING AT HIGHER WATER CONTENT IN FOODS • FRUITS AND VEGETABLES ARE OVER 70% WATER • FOODS CONSIDERED DRY CONTAIN WATER • BREAD IS 36% WATER • POPCORN IS 4% WATER • WATER BECOMES PART OF FOOD IN 2 MAIN WAYS: • AS FREE WATER • AS BOUND WATER WATER CONTENT IN FOODS • FREE WATER: WATER THAT IS EASILY SEPARATED FROM FOOD TISSUES • BOILS AND FREEZES EASILY • BOUND WATER: WATER THAT IS TIED TO THE STRUCTURE OF LARGE MOLECULES • DOES NOT BOIL OR FREEZE EASILY • CHEMICALLY REACTS AS PART OF THE LARGER MOLECULE TO WHICH IT IS BOUND FUNCTIONS OF WATER IN THE BODY • MAINTAINS BODY TEMPERATURE • WHEN BODY TEMPERATURE RISES, WATER IS RELEASED FROM THE BODY • AS SWEAT EVAPORATES, IT PULLS EXCESS HEAT AWAY FROM YOUR BODY • TRANSPORTS NUTRIENTS • MINERALS AND WATER-SOLUBLE VITAMINS DISSOLVE IN WATER BEFORE THEY ARE TRANSPORTED TO WHERE THEY ARE NEEDED • TRANSPORTS WASTE PRODUCTS OUT OF THE BODY FUNCTIONS OF WATER IN THE BODY • SERVES AS A REACTANT IN THE METABOLISM • EX: YOUR BODY USES WATER TO BREAK DOWN THE ENERGY NUTRIENTS DURING DIGESTION • BECOMES PART OF BODY TISSUE • BODY IS COMPOSED OF 60% WATER • ALL BODY FLUIDS ARE LARGELY COMPOSED OF WATER MEETING YOUR BODY’S WATER NEEDS • 6-8 GLASSES OF WATER A DAY • CAN LIVE MUCH LONGER WITHOUT FOOD THAN YOU CAN WITHOUT WATER • SHOULD DRINK WATER RATHER THAN JUST GETTING WATER FROM FOODS 1. WATER ITSELF HAS NO CALORIES 2. MANY FOODS THAT ARE HIGH IN WATER ARE ALSO HIGH IN SUGAR AND SALT ROLE OF THIRST • THIRST IS ONE WAY YOUR BODY LETS YOU KNOW YOU NEED WATER • BODY NEEDS WATER BEFORE YOU FEEL THIRST AND AFTER YOUR THIRST APPEARS TO BE QUENCHED • THIRST DOES NOT OCCUR UNTIL WATER SUPPLIES ARE ALREADY LOW • SHORTAGE OF WATER CAN LOWER ENERGY LEVELS, REDUCE COORDINATION, AND BEGIN TO DAMAGE BODY TISSUES • ICE WATER RELIEVES THIRST FASTER THAN WARM WATER • WATER EVAPORATES FROM SKIN AND THROUGH BREATH AT HIGH ALTITUDES WHERE ATMOSPHERIC PRESSURE IS LOW A SAFE WATER SUPPLY • IMPURITY: ANYTHING ADDED TO A COMPLETE PURE SUBSTANCE • SALT AND MICROORGANISMS ARE IMPURITIES SOMETIMES FOUND IN WATER • IMPURITIES CAN CHANGE WATERS BOILING POINT, FREEZING POINT, AND HYDROGEN BONDING • HOT TAP WATER CAN CONTAIN MORE IMPURITIES THAN COLD TAP WATER A SAFE WATER SUPPLY • CONTAMINANT OR POLLUTANT: ANYTHING THAT MAKES A SUBSTANCE IMPURE OR UNSUITABLE • COMMON SOURCES ARE ANIMAL AND HUMAN WASTES, CHEMICALS, AND GARBAGE A SAFE WATER SUPPLY • BIOLOGICAL POLLUTANT • BACTERIA, VIRUSES, AND ORGANIC WASTES • IN LARGE VOLUMES, CAN DEPLETE OXYGEN LEVELS IN RIVERS AND LAKES • CHEMICAL CONTAMINANTS IN WATER • METAL IONS, ACIDS, AND TOXIC SUBSTANCES • PHYSICAL POLLUTANTS • GARBAGE AND LITTER A SAFE WATER SUPPLY METAL IONS • HARD WATER: WATER THAT CONTAINS CALCIUM OR MAGNESIUM IONS • INTERFERES WITH WATER’S TENDERIZING EFFECT • DRIED BEANS, PEAS, AND LENTILS MUST COOK LONGER IN HARD WATER • EASILY REMOVED THROUGH HEATING • PERMANENTLY HARD WATER ALSO ADDS SULFUR AND CHLORIDE COMPOUNDS THAT MUST BE REMOVED THOUGH AN ION EXCHANGE METHOD USING WATER SOFTENER A SAFE WATER SUPPLY ACIDS • CHANGE THE PH OF WATER • EX: ACID RAIN • THE MORE CARBON DIOXIDE THAT DISSOLVES IN RAIN, THE LOWER THE PH OF RAINWATER • LOWER PH LEVELS CAN KILL PLANT/ANIMAL LIFE • OTHER ACIDS INCLUDE: SULFURIC ACID, NITROGEN OXIDES, AND HYDROCHLORIC ACID