Chapter 4: Water- It's chemical and Physical Properties

Question 1

Element… atom?

Answer 1

substance that can not be broken apart into different substances by ordinary chemical methods… smallest form of an element is an atom

Question 2

molecule?

Answer 2

two or more atoms of one element or of different elements combined to form another substance

Question 3

What are atoms composed of?

Answer 3

a nucleus that contains a proton (not always), neutrons, and electrons that move about in the space surrounding the nucleus

Question 4

Covalent and ionic bond

Answer 4

result of gain, loss, or sharing of electron (s) between and among atoms. these gains, losses, and sharing are based on the “need for charge neutrality in an atom, and for a specific arrangement of the atom’s electrons

Question 5

What needs to be done to have a stable atom?

Answer 5

There needs to be two electrons
ex: Hydrogen has one electron and proton, but it needs another electron to be stable, so it shares an electron with another hydrogen making hydrogen gas (H2)- this is called a covalent bond (the sharing of an electron by the nuclei of two atoms makes a strong molecule)

Question 6

Ionic bond?

Answer 6

Lose or acquire electrons
ex: sodium chloride - chlorine has eight electrons, while sodium has one, and its unstable so it want to lose it or get eight electrons, so chlorine snatches it and then become charged ions (Cl- and Na+) so now they attach bc opposites attract and form a crystalline lattice of atoms held by an ionic bond, until water dissolves the bond

Question 7

hydrogen bond? Water molecule (polar molecule)? Cohesion?

Answer 7

atoms that have had the position of their electrons altered

water molecules, as a whole, has a positive charge on the side with the two hydrogen atoms, and a negative charge on the other (thus making it a polar molecule)- and bc opp attract, it’ll attract other water molecules- boom hydrogen bond

Weak-> altered by temperature; more hydrogen bonds in cold waters than there are in warmer waters (why water is less dense in warm water? and denser in cold water?- water being more close or tight together in cold, and not so together in warm water, is a process called cohesion)

Question 8

Surface tension?

Answer 8

the tension created among those molecules at the air-water interface produces a skin-like surface; a volume of water is held together by surface tension

Question 9

Water dissolving salt?

Answer 9

The individual sodium and chloride ions in the NaCI crystalline lattice becomes surrounded by water molecules (when water is poured); and the positive sodium ion (Na+) attracted to the negative end of the water molecule (oxygen); while Chloride (Cl-) is attracted to the positive side (H+), and it frees them from their crystalline lattice (and mixes)

Question 10

Water’s heat capacity? heat and temperature

Answer 10

Water -high
heat: a measure of energy; includes the information of how many molecules are moving within a given volume (that’s why a lit of hot air does not have as much heat as a liter of water at the same temp; there are more molecules in a liter of water than there are in a liter of air; bottle of air heat would change temp after than water)
temperature: the measure of speed of motion of atoms and molecules

Question 11

Calorie?

Answer 11

Measures the change in temperature of the heated-substance, term the amount of energy required to a heat volume of water at a certain temperature

Question 12

water’s high heat capacity? What does it mean in regards to the world?

Answer 12

because the earth has a high heat capacity, it is important in regulating, moderating, and driving our weather and climate

Question 13

Ocean in summer and winter?

Answer 13

Costal regions are cooler, bc earth takes in the heat etc., during summer, it’ll take the heat too - cools the land, happening because of it’s high heat capacity which is a result of hydrogen bonds

Question 14

two type of heats when it comes to water?

Answer 14

1) sensible heat: heat that can be sensed with a thermometer
2) latent heat: hidden, proven through an experiment (add heat to a gram of ice)

Question 15

Latent heat of melting and latent heat of vaporization?

Answer 15

1) up till 80 calories does the ice melt, and becoming a liquid (ice to liquid)
2) 540 calories per gram (higher than the latent heat of evaporation) (heat to liquid) (meaning we can put a wet towel in front of a fan, and the room will be cooler bc 540 calories of room heat is absorbed every gram of moisture evaporated from the wet cloth- it will also be more humid)

Question 16

Salts and salinity?

Answer 16

salt: chemical compounds in which a metal is bound with a nonmental
salinity: which is defined as the total quantity, by weight, of dissolved inorganic solids in seawater (35 parts per thousand bc no one says 3.5%)

Question 17

What happens to rivers that discharge volumes of freshwater into the ocean?

Answer 17

Freshwater gets diluted (made thinner or less intense by mixing something else) by mixing with the ocean; this makes rivers salinity be controlled by the proximity or rivers

Question 18

Why are oceans salty?

Answer 18

In the open ocean, salinity is controlled by the differences in evaporation and precipitation- evaporation removes only pure water, leaving the salt behind and increasing salinity

Question 19

Where are the oceans the saltiest?

Answer 19

Makes sense for it to be the tropical or subtropics because of
warmth and warmth means more evaporation, but at the equator, the evaporated moisture in the atmosphere does not travel very far north or south, falls back to the ocean in the same latitude- also lots of clouds, less direct light, less evaporation - most evaporation is at subtropical areas, lot of precipitation in temperate areas (high evaporation rates in eastern Mediterranean (>39 ppt)

Question 20

Where are the sources of salt for the ocean?

Answer 20

1) rivers
2)mid-ocean ridges (responsible for manganese, iron, zinc, lithium, and cesium , also a sink for sulfate and magnesium)
3) undersea and terrestrial volcanoes
4) majority from the weathering of continents

Question 21

If the volcanoes, the weathering of continents, etc., all are the cause of salt, then is the sea going to continue to get saltier?

Answer 21

No, the oceans have reached a steady rate with salinity

basically, the amount of dissolved material continually being added to the oceans has reached an equilibrium with the amount being lost from the oceans by way of chemical and biological precipitation processes and subsequent burial in sediments

Question 22

Density?

Answer 22

Mass per unit volume; varies with temperature and salinity (not constant)

Question 23

temperature and warmth?

Answer 23

temperature: measure of how rapidly molecules (and atoms) are vibrating and moving around

molecules of a warmed substance will “bump into one another” at a faster rate, forcing the molecules further apart and increasing its volume= less dense than cold water

Question 24

density and temperature: cluster effect?

Answer 24

basically, when water temp cools at 3.98%, a cluster effect occurs, which means that the formation of tetrahedrons now dominate the change in density, so that rather than continuing to get denser, it just gets lense dense (bc its uniformed and looks like a beehive)

Question 25

cluster effect vs normal temperature effect

Answer 25

cluster effect: increases the volume and decreases the density, works against the normal temperature effect; more important; more tetrahedrons, so the DENSITY DECREASES (valid at 3.98 degrees celsius) and boom ice (which is full of hexagons)

normal temperature effect: whereby lowering the temperature reduces the speed of molecular vibrations and reduces the volume of molecules occupy; increasing the density (not valid when it is below 3.98 degrees celsius)

Question 26

Dissolving salt and density?

Answer 26

dissolving salt in water increases the salinity and the density bc there is more material (so mass increases, but not volume - it actually decreases bc things are more packed, and that’s why density increases)

mass increases + volume does not = more density

Question 27

thermocline?

Answer 27

a depth interval where the temperature changes rapidly

Question 28

What happens with the surface water of a lake becomes denser than the (warm) water below it?

Answer 28

The surface water is then replaced with warmer and less dense water. The denser ssw is replaced with the less dense one and it does so until everything is the same temperature (meaning isothermal). This is called fall overturn!

happens in the ocean too, dense water gets mixed with the thermocline

Question 29

What happens to the salinity when salt is added?
What happens when salt is increased in regards to density?

Answer 29

1) salinity decreases the heat capacity by 4%
2) -increasing salinity, increases density

Question 30

what happens to the temperature of maximum density when salt is increased?

Answer 30

3) the maximum density is no longer 3.98 degrees Celcius ; it becomes significantly lower, depending on how much salt was added; why? salt interacts with charged ends of water molecules and thus interferes with the formation of hydrogen bonds and impedes the formation of tetrahedrons and clustered; the importance of clusters decreasing the density of water is suppressed in water; so basically as salt water cools, the normal temperature effect increases density faster than it does in fresh water over the same temperature range

Question 31

How do freshwater and saltwater respond to changes in temperature?

Answer 31

1) salt interferes with hydrogen bonding, so seawater increases faster as the temperature drops, giving a steeper curve
2) cluster effect never does result in density reversing as temperature drop, the way it does in freshwater - seawater just continues to get dense and denser with decreasing temperature

Question 32

What happens when you add salt to the water?

Answer 32

it lowers the freezing point; why salt added to roadways to prevent freezing and melt ice; which is why salt impedes the formation of hydrogen bonds and the formation of clusters

adding salt to freshwater will decrease heat capacity, increase density, lower the temperature of maximum density
unlike freshwater, salt water reaches its maximum density before it freezes

Question 33

What happens when water gets cold in the ocean, unlike freshwater?

Answer 33

It just continues to get even colder, and go even below -2 degrees celsius and the surface can freeze over, which why the ocean rarely ever freezes

Question 34

why is sea ice less brittle than ice elsewhere?

Answer 34

When it freezes, the dissolved salt in that water is excluded from the crystalline lattice, leaving a salty brine, which leaves holes (known as air pockets)

Question 35

what happens to density when pressure is increased?

Answer 35

density increases bc it is basically getting compressed (hard but simple at the bottom of the ocean)

Question 36

How does temperature and salinity affect density?

Answer 36

as temperature increases; density decreases

as salinity increases: density increases

Question 37

What would happen if we were to mix two different sea waters?

Answer 37

we would get the average of their temperature and salinity, while we would get a volume of water that is even DENSER than what either of the two-volume of water had, the new mixture would sink

Question 38

What do we call temperature, salinity, and density in regards to depth of the ocean? (the chart)

Answer 38

thermocline, halocline, pynocline - they all indicate a change in temperature, salinity, and density

Question 39

Speed of sound in the water? what are the two factors and what has a greater impact?

Answer 39

temperature and pressure- temperature has the greater effect

as temperature increases and pressure inceases- sound travels faster

Question 40

upper mixed layer? below it?

Answer 40

layer near the surface of relatively uniform temperatures, having been mixed by surface winds and waves - thermocline (where temperature gets colder with increasing depth)