Suffolk Public Schools Blog - Salt and the...
Transcript of Suffolk Public Schools Blog - Salt and the...
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Salt and the Ocean
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Atomically Speaking…• Ions are atoms with either more or less electrons
than protons and are therefore electrically charged.
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When water and salt mix…• Water dissolves salts by surrounding the atoms in
the salt molecule and neutralizing the bond holding the molecule together.
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When water and salt mix…• Water dissolves salts by surrounding the atoms in the salt molecule and neutralizing the bond holding the molecule
together.
– Dissolved salts form cations (positively charged ions) and anions (negatively charged ions).
– The process of water surrounding an ion is called hydration.
//upload.wikimedia.org/wikipedia/commons/2/29/Ions.svg//upload.wikimedia.org/wikipedia/commons/2/29/Ions.svg
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• Seawater consists of water with various materials dissolved within it.
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– 1. The solvent is the material doing the dissolving and in seawater it is the water.
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– 1. The solvent is the material doing the dissolving and in seawater it is the water.
– 2. The solute is the material being dissolved, and in seawater it is the salt.
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– 1. The solvent is the material doing the dissolving and in seawater it is the water.
– 2. The solute is the material being dissolved, and in seawater it is the salt.
– 3. A solution is the combination of the solvent and solute.
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– 4. Salinity is the total amount of salts dissolved in the water.
• a. It is measured in parts per thousand and is expressed as pptor abbreviated 0/00.
• How salty do you think the ocean is?
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– 5. Average salinity of the ocean is about 35 0/00.
• Draw this diagram:
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Not just one salt…• 99% of all the salt ions in the sea are sodium (Na+),
chlorine (Cl-), sulfate (SO4-2), Magnesium (Mg+2),
calcium (Ca+2) and potassium (K+).
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Not just one salt…–1. Sodium and chlorine alone comprise
about 86% of the salt in the sea.
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Not just one salt…–2. The major constituents of salinity display
little variation over time and are a conservative property of seawater. This means that what is taken out is replaced equally.
SALT OUT
SALT IN
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Nutrients are chemicals essential for life
• 1. Major nutrients in the sea are compounds of nitrogen, phosphorus, and silicon.
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Nutrients are chemicals essential for life
• 2. Because of usage, nutrients are scarceat the surface and their concentrations are measured in parts per million (ppm).
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Nutrients are chemicals essential for life
• 3. Concentration of nutrients varies greatly over time and because of this they are considered a non-conservative property of the sea.
• This means that what is taken out is not replaced.
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The sea contains dissolved gases, elements, and other compounds…
• In order of decreasing abundance the major gases in the sea are nitrogen, oxygen, carbon dioxide and the noble gases: argon (Ar), neon (Ne) and helium (He).
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The sea contains dissolved gases, elements, and other compounds…
–1. Nitrogen and the noble gases are considered to be inert because they are chemically non-reactive. This means they like to be alone!
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The sea contains dissolved gases, elements, and other compounds…• In order of decreasing abundance the major gases in the sea are nitrogen, oxygen, carbon dioxide and the
noble gases: argon (Ar), neon (Ne) and helium (He).
– 1. Nitrogen and the noble gases are considered to be inert because they are chemically non-reactive. This means they like to be alone!
• Trace elements occur in very small quantities and are usually measured in parts per million (ppm) or parts per billion (ppb).
– 1. Even in small quantities they are important in either promoting life or killing it.
Some of the trace elements of ocean water: Ag, Al, As, Au, B, Ba, Be, Bi, Br, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga Gd, Ge, Hf, Hg, Ho, In, K, La, Li, Lu, Mn, Mo, Na, Nb, Nd, Ni, Pa, Pb, Pd, Pr, Pt, Ra, Rb, Re, Ru, Sb, Sc, Se, Si, Sm, Sn, Ta, Tb, Th, Ti, Tl, Tm, V, W, Y, Yb, Zn, Zr.
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//upload.wikimedia.org/wikipedia/commons/2/29/Ions.svg//upload.wikimedia.org/wikipedia/commons/2/29/Ions.svg
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Quiz Next Class!
• Conservative Property of Seawater
• Solute
• Solvent
• Anion
• Inert
• Nutrients
• Non-Conservative Property of Seawater
• Solution
• Cation
• Ion
• Salinity
• Trace Elements
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To Salinity and Beyond!
• Salinity in the ocean is in a steady-state condition because the amount of salt added to the ocean (input from source) equals the amount removed(output into sinks).
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To Salinity and Beyond!• Salinity in the ocean is in a steady-state condition because the amount of salt added to the ocean (input from source)
equals the amount removed (output into sinks).
– 1. Salt sources include weathering of rocks on land and the reaction of lava with seawater.
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To Salinity and Beyond!• Salinity in the ocean is in a steady-state condition because the amount of salt added to the ocean (input from source)
equals the amount removed (output into sinks).
– 1. Salt sources include weathering of rocks on land and the reaction of lava with seawater.
• a. Weathering mainly involves the chemical reaction between rock and acidic rainwater, produced by the interaction of carbon dioxide and rainwater forming carbonic acid.
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• Salt sinks (drains on salinity) include the following:
– 1. Evaporation removes only water molecules.
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• Salt sinks (drains on salinity) include the following:
– 1. Evaporation removes only water molecules.
• A. Remaining water becomes increasingly saline, eventually producing a salty brine.
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• Salt sinks (drains on salinity) include the following:
– 1. Evaporation removes only water molecules.
• A. Remaining water becomes increasingly saline, eventually producing a salty brine.
• B. If enough water evaporates, the brine becomes supersaturate and salt deposits begin to precipitate forming evaporite minerals (HYDROGENOUS DEPOSITS!)
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• Salt sinks (drains on salinity) include the following:– 1. Evaporation removes only water molecules.
• i. Remaining water becomes increasingly saline, eventually producing a salty brine.
• ii. If enough water evaporates, the brine becomes supersaturate and salt deposits begin to precipitate forming evaporite minerals (HYDROGENOUS DEPOSITS!)
– 2. Wind-blown spray carries minute droplets of saltwater inland.
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• Salt sinks (drains on salinity) include the following:– 1. Evaporation removes only water molecules.
• i. Remaining water becomes increasingly saline, eventually producing a salty brine.
• ii. If enough water evaporates, the brine becomes supersaturate and salt deposits begin to precipitate forming evaporite minerals (HYDROGENOUS DEPOSITS!)
– 2. Wind-blown spray carries minute droplets of saltwater inland.
– 3. Absorption of ions onto clays and some authigenicminerals.
http://www.bibledoctrine.20fr.com/http;/www.bibleplaces.comhttp://www.bibledoctrine.20fr.com/http;/www.bibleplaces.com
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• Salt sinks (drains on salinity) include the following:– 1. Evaporation removes only water molecules.
• i. Remaining water becomes increasingly saline, eventually producing a salty brine.
• ii. If enough water evaporates, the brine becomes supersaturate and salt deposits begin to precipitate forming evaporite minerals (HYDROGENOUS DEPOSITS!)
– 2. Wind-blown spray carries minute droplets of saltwater inland.
– 3. Absorption of ions onto clays and some authigenic minerals.
– 4. Shell formation by organisms.
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Salt affects water’s unique properties…
• Addition of salt modifies the properties of water.
– 1. Pure water freezes at 0oC. Adding salt increasingly lowers the freezing point because salt ions interfere with the formation of the hexagonal structure of ice.
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Demo Time!1. What is in the graduated cylinders at the front?
2. What did the egg do in #1? #2? #3?
3. What do you think is in each of cylinders?
4. What property of water is being affected in this demonstration?
5. What is the secret to cylinder #3?
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Salt affects water’s unique properties…• Addition of salt modifies the properties of water.
– 1. Pure water freezes at 0oC. Adding salt increasingly lowers the freezing point because salt ions interfere with the formation of the hexagonal structure of ice.
– 2. Density of water increases as salinity increases.
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Salt affects water’s unique properties…• Addition of salt modifies the properties of water.
– 1. Pure water freezes at 0oC. Adding salt increasingly lowers the freezing point because salt ions interfere with the formation of the hexagonal structure of ice.
– 2. Density of water increases as salinity increases.
– 3. The boiling point of water increases.
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Videos
• http://www.jpl.nasa.gov/video/index.cfm?id=984
• http://app.discoveryeducation.com/player/view/assetGuid/1D6C88E0-C080-42BE-BB12-D8FEEEAB8399 (downloaded and emailed)
http://www.jpl.nasa.gov/video/index.cfm?id=984http://app.discoveryeducation.com/player/view/assetGuid/1D6C88E0-C080-42BE-BB12-D8FEEEAB8399