1.3 water and life

liquid vs frozen water

-liquid = more dense

-frozen = less dense (stays apart a bit more)

water molecule

-y shape

-polar covalent bonds = oxygen more electronegative thatn hydrogen

Surface tension

• Measure of how difficult it is to stretch/break surface of a liquid

• When air-water meet/interface

  • -> water molecules ordered arrangement = bonded to one another

    • -> NOT BONDEDTO AIR because duh, can only bond to each other
      Because x bond to air/presence of air itself kind of-> hold on extra tight to each other

    • -> added strength to each other -> more difficult to break through surace

    • -> aka surface tenison!

• Moderation of temperature by water

• Absorb heat from warmer air

  • Releases stored air into cooler air

  • -> water is basically a heat bank = take a lot without changing its own temperature a lot

• Heat and temperature

• Anything that moves = kinetic energy

  • ^ speed -> ^ kinetic energy

thermal energy

• Random movement by atoms/molecules

• (ALL KINETIC ENERGY THAT FACOTRS IN VOLUME)

• Temperature

• Average kinetic energy of molecules in a body of matter regardless of volume

thermal energy vs temperature

• E.x Water heated in coffemaker -> speed of molecules increase

  • -> rise in temperature

  • HOWEVER DIFF THAN THERMAL ENERGY

    • Coffee maker has hotter temp than a pool, because volume x counted

    • HOWEVER a pool is larger and therefore has more volume, and therefore has more therhmal energy

when two objects of different temerpatures of brought together

• • Thermal energy from warmer -> goes to cooler to make them same temperature

  • E.x ice cube absorbs thermal energy -> making it less cool

heat

Thermal energy transferred from one body of matter to another

Calorie (cal)

• Amount of heat it takes to raise the temperature of 1g of water by 1C

• OR

• Amount of heat that 1g of water release when it cools by 1 C

• Kcal (1000cal) = 1kg of water

• Joule (j) 

  • 0.239 cal = 1j

  • 1cal=4.184j

• Specific heat

• Amount of heat that must be absorbbed/lost for 1 g of it to have its temperature change by 1 C

• Measured in CALORIES

  • -> specific heat of water = 1 cal per 1 gram per degree celsius (per degree celsius just emans to raise it up by 1 celsius)

    • Aka 1cal/g*C

• Can also be thought of how well substances resits temperature changes

• Water very HIGH specific heat

• E.x ethyl alcohol = 0.6cal/g*C 

• E.x water in contrast

  • Will change its temperature less than ther liquids when aborbsing/losing heat

  • -> e.x when u burn yourself on the iron pot, its because the iron is receiving the immense amount of heat needed to make the iron inside of it hot

    • -> therefore iron temperature raises much faster

? why so high = hydrogen bonding

• Heat must be absorbed to break bonds

  • Inverse = when bonds are made, heat is released

  • -> less heat = more bonds -> releases high energy in form of heat

  • Takes so much because initial heat is used to break the bonds itself, not even starting to move them round

• Evaporative cooling

• Molecules of any liquid = close together due to attraction

• Molecules -> move fast -> resist attractions -> serpate/depart the liquid -> escape into air

  • -> enter a gas/vapor state

  • = vaporization/evaportization

• To evaporate -> x always need high temp = room temp water will event evaporate

  • When heated tho = ^ kinetic energy of molecules -> faster evaporation

• Heat of vaporization

• Quantity of heat a liquid must absorb for 1g of it to turn intoa  gas

• Water has a high heat of vaporization 

  • 580cal of heat -> evaporate 1g at 25c 

  • Due to hydrogen bonds

    • Must be broken before molecules can exit from the liquid

Evaporative cooling

• Evaporative cooling

  • = as a liquid evaporates on the top, the new made surface of the liquid that remains behind cools down (temp decrease)

  • Hottest molecules = those w/greatest kinetic energy 

    • -> more likely to leave as a gas

    • -> removes overall heat and there with it cools

  • -> stability of temperatures in lakes/ponds

    • -> prevents terrestrial organisms from overheating

      • Evaporation of water from the leaves of a plant = keeps tissue in leaves from becoming to warm/cools down the leaf

      • Evaporation of sweat from human skin = lowers body temp = prevents overheating 

      • High humidity - high conteration of water vapor in the air stops evaporation of sweat -> discomfort

• Floating Ice on liquid water

• Water

  • = more dense as liquid (rare)

    • Other materials usu contract/become denser when solidified, while water expands

  • -> ice floats on liquid water (less dense)

why more dense?

• Why more dense?

  • Hydrogen bonds

  • Above 4C

    • Water = expands when warms

    • Water = contracts when cool

  • 4C-0C

    • Water -> freezes

      • = molecules are to slow to break hydrogen bonds

      • -> become locked into crystalline lattice

      • -> hydrogen molecule binds to four others like a big 5 circle shape

      • -> molecules keep a arms length/distatance from aech other

      • -> 10% less dense

    • -> when gains back heat

      • -> melts ice -> disrupts hydrogen bonds

        • Get closer together/constantly moving

        • -> as it gets hotter beyond 4C begins to expand + molecules faster

      • -> crystal collapses

• Importance = allows life on earth to thrive in certain enviroments

  • Ponds, lake, etc freeze over ON TOP

solution, sovlent, solute

• Solution

  • Liquid that is homogenous (made of the same material e.x when u stir chocolate milk so its cohesive) mixture of two or more substances

• Solvent

  • Thing that acts as the agent in dissolving the solute

• Solute

  • Substance being dissolved

aqueos solution

• Aqueous solution

  • Water = solvent

    • Very versatile = due to polarity

      • E.x sodium chloride placed into water

      • -> each ion of sodium/chloride are exposed to hydrogen/oxygen 

        • -> h/o attracted to due their pos/neg charges

          • -> oxygen = neg -> sodium cations

          • -> hydrogen = pos -> chloride anions

          • -> attraction serpates them from one another because each are attracted to the other

          • -> sphere of water molecules around each dissolved ion = hydration shell

      • -> fully separated -> results in a solution of two solutes = sodium cations and chloride anions

      • Does not have to be ionic -> can be nonoic polar molecules e.x sugar, even big proteins if ionic/polar regions

        • = dissolve when water molecules make hydrogen bonds/wsolute molecules

hydrophollic

• Hydrpohlic

  • Substance = love water = aka ionic.polar ->  no hydrogen bonds

    • X have to dissolve to be hydrophilic

      • E.x some to large to dissolve 

        • cotton = giant molecules of cellulose = polar -> can hydrogen bond -> water adheres to it 

          • = cotton does a good job of drying body, but x dissolves in washing machine

        • Hydrpolic walls in water conducting cells helps move water up a plant against gravity

hydrophobic

• nonionic/nonpolar -> no hydrogen bonds

  • E.x vegetable oil

    • -> x mixes w/water-based substances (e.x vinegar)

    • = many nonpolar covalent bonds

• Important ingredient for cell membrambe

  • -> cell membrane x dissolve or else entire cell would be fucked

how water changes pH

• Hydrogen atom in a hydrogen bond w/ other water molecules 

  • Hydrogen shifts from one molecule to another

    • -> 1 hydrogen (proton) leaves H2O

    •  -> turns H2O it left negative (more electrons than protons)

      • hydroxide ion (OH-)

    •   -> H+ binds to the other water molecule

      •  H3O+ 

      • Turns hydrogen ino positive (because less electron=unbalanced)

      • Turns water molecule it left into negative (extra electron w/o proton from hydrogen to balance it out)

synposis

• -> water molecule that lost a hydrogen/ = hydroxide ion (OH-)

• -> run away H binds to other hydrogen = hydronium H3O+)

H3O=H

acids

• Acid

  • Substance that increases hydrogen ion concentration of a solution (creates hydrogen ions) by separating entire compounds

    • Ex.hydrochloric acid -> added to water -> hydrogen ions serpate from chloride ions

      • -> HCI -> (water) -> H+  + Cl-

-= not only add hydrogen ions, also remove hydroxide ions

• -> tendency for H+ to combine with OH- -> making water

weak acids

• Weak acids

  • Acids that reversibly release and accept back hydrogen ions 

    • X SERPATE ENTIRE COMPOUND ONLY REMOVES H+

    • (out and then back in)

    • E.x carbonic acid

      • H2CO3 (carbonic acid) -> HCO3- (bicarbonate ion) + H+

      • Carbonic acid x fuly breaks apart, only hydrogen leaves, BUT enough to add more H+ concreation

bases

• Base

  • Substance that reduces the hydrogen ion concentration of a  solution (brings H+ into entire compounds/serpating compounds that make hydrogen ions)

    • Some reduce H+ concentration by accepting hydrogen ions

      • E.x amonima (NH3)

        • -> electron pair in nitrogens valence shell 

        • -> attracts a hydrogen ion from a solution

        • -> results in ammonium ion (NH4+)

    • Some reduce H+ concentration by dissociating/serpating the molecules to form hydroxide ions

      • E.x sodium hydroxide 

- not only add OH- concentration but also reducing H+ = forming water

summary

• When H+ and OH- are equal -> neutral

• More OH- than H+ = basic (neg

• More H+ than OH- = acidic (pos

pH

• pH= -log[H+]

  • [H+] 

    • The concentration of hydrogen protons

      • moles per liter (mol/L).

  • -log 

    •  The logarithm (base 10), 

buffers

• Buffers

  • Substance that minimzes changes in the ceontration oh H+ and OH-

    • E.x why does more acids impact water so much more than other things

    • How?

      • Accepts hydrogen ions from the solutions when in excess

      • Releases hydrogen ions into the solution when depleted

    • Most are have a weak acid + its corresponding base

ocean adicification

• Ocean acidification

  • Burning of fossil fuels

    • -> releases CO2

    • -> global warming

  • 25% of CO2 made by humans

    • -> absorbed by oceans

    • -> when dissolves into water

    • -> reacts and forms carbonic acid

      • Carbonic acid releases hydrogen ions in water 

      • Hydrogen ions combine w/carbonate ions CO3^2- present in ocean

        • -> HCO3- (bicarbonate ions)

        • -> reduces carbonate ion concentration (pred. -40%)

        • Why bad? = carbonate ions are need to make calcium carbonate 

          • E.x reef building corals and shells

    • -> loweres ocean pH

      • Detected by measuring the CO2 level in air bubbles trapped in ice

      • -> ocean = 0.1pH unit lower than any time in the last 420,000 years