Happy 2nd day of Spring Semester! Please have on your desk, if completed: your signed SCAT hrs sheet, parent letter, info sheet, safety & survey If you brought water, please make sure your name and the location (where you got it) is on it. Openers- most days you will have an opener, keep a running log of them (you could see them again…) Lab Info (You might want to jot this down) EVERY LAB/ACTIVITY HAS A SUMMARY!!! (WHAT YOU LEARNED; USE VOCABULARY…) Do not tell me what you learned ABOUT, tell me what you specifically learned/reviewed/how it works… If you are absent: copy the lab and write at the top: “I got this from….” and write your own summary.
Opener, Wed. Jan. 21st Hydro: Sal- or Hal(o)-: -cline: Refract-: Picno-: Thermo-: List all properties of water that you can think of!!
Seawater Chemistry
Without water, there would be no: Oceans no lakes no rivers no rain or snow or hail no clouds or no polar ice caps no cold beverages or anything to drink whatsoever probably no you, no me, no nothing!
Water Rules! Water is everywhere! It defines our planet! It is intricately involved in just about every process on this planet!
Ten properties of water that are familiar to us all: It's colorless It's tasteless It's odorless It feels wet It's distinctive in sound when dripping from a faucet or crashing as a wave It dissolves nearly everything It exists in three forms: liquid, solid, gas It can absorb a large amount of heat It sticks together into beads or drops It's part of every living organism on the planet.
How does this simple molecule, merely 2 hydrogen atoms and 1 oxygen atom (H2O) do all the amazing things that it does? That's what we are about to find out!
Water is Polar (not like cold!!) Polarity: Water is a covalent molecule Electrons are not shared equally so…
Hydrogen Bonds Hydrogen bonds
Water dissolves almost anything! "Universal Solvent” – Why??
Drawings:
The Dissolving Power of Water As solid NaCl dissolves, + and - ions are attracted to the + and - ends of the polar water molecules. Water surrounds ions!
Salinity Salinity = The various ions dissolved in seawater Avg. ocean = Salt flat in Bolivia
Avg. ocean = 35 ppt (‰)
Major ions in seawater Chloride (Cl-) Sodium (Na+) Sulfate (SO42-) Concentration (ppt) Percentage % Chloride (Cl-) 19.3 55 Sodium (Na+) 10.7 30.6 Sulfate (SO42-) 2.7 7.7 Magnesium (Mg2+) 1.3 4 Calcium (Ca2+) 0.4 1.18 Potassium (K+) 1.11
Principle of constant proportions
Principle of constant proportions Example: in any sample of seawater, whether it has a salinity of 20 ppt or 40 ppt, chlorine accounts for 55% of the ions, sodium comprises 30.6%, sulfate makes up 7.7% and magnesium measures out at 4%.
Factors affecting salinity Evaporation/freezing = Frequent precipitation = PRECIP > EVAP PRECIP < EVAP
Opener: Jan. 22nd Write the questions, then answer… Explain how a refractometer works: what does it measure and how does it do it? Why did the two colors of seawater sink/float yesterday?
Salt wedge fresh water from inland and salty ocean water meeting in estuaries, form a “salt wedge”
Salinity & Density Lab Drawings & profile graphs
Measuring salinity Hydrometer Refractometer Conductivity meter
Sources of Salt Run-off Hydrothermal Vents Volcanoes http://www.ceoe.udel.edu/extreme2004/geology/hydrothermalvents/index.html Volcanoes
What can add salts? Run-off, vents, volcanoes
Sources of salts What can remove salts? Vents, organisms, shells Ions in = ions out (salt ratios stay the same!)
Density
Heat vs Temperature
Heat vs Temperature 100 degrees Celcius 100 degrees Celsius Which container has molecules with the higher average kinetic energy? Which container has the most heat energy?
Water- has a high heat capacity! Water has the highest heat capacity of any liquid or solid, except ammonia. heat capacity of a substance =
Water can absorb a tremendous amount of heat! How does salinity affect heat capacity? Ocean temp. varies much less than land Why??
You experience this here!!! Anyone who has lived near the beach has probably noticed the heat buffer- days are not as hot during summer and nights are not as cold during winter!
High heat capacity allows the Atlantic to absorb and release tremendous amounts of heat without changing temperature!
Sea surface temps vary from very warm (86 degrees) in tropics to below freezing at poles.
Temperature - Very important! Only freshwater freezes in the ocean, leaving a very salty layer underneath (what will it do??) Deep ocean =very cold Thermocline = When fishing offshore you may look for the thermocline—holds bait, etc.
This beach is covered in SNOW… why isn’t the ocean frozen?! Salt Ocean currents High volume Earth’s internal heating
ICE CREAM LAB RECAP! Salt in the ocean lowers FP from 32F (0C) to 28F (-2C) “FP Depression” There are other factors involved, but this helps our oceans NOT freeze at 32F! Adding the salt makes the ice melt, because we’re above the freezing point. To melt the ice, the ENERGY is taken from the MILK…which makes it FREEZE!