Water Chapter 1 Study Guide & Outline PDF

Aarav Reddy Chapter 1 : Water 1.1 - Particle Theory and Bonding 1.1.1 explain the changes of state in water, between solid, liquid and gas, in terms of the kinetic particle theory (kinetic) particle theory – all matter contains particles that are in constant , motion even if...

Aarav Reddy Chapter 1 : Water 1.1 - Particle Theory and Bonding 1.1.1 explain the changes of state in water, between solid, liquid and gas, in terms of the kinetic particle theory (kinetic) particle theory – all matter contains particles that are in constant , motion even if they are just small vibrations o that motion is determined by the amount of energy the particles contain and their relationship to other particles as energy is transferred away/to these molecules , the state of matter may change as the movement of the molecules change solid → liquid : melting : when ice is heated , energy is added to the water molecules making them vibrate faster , causing them to break apart from each other and flow away liquid → gas(water vapor) : evaporation : when liquid water is heated , particles gain energy , moving faster and further from each other (some collisions transfer enough energy for them to evaporate) o boiling point : 100 degrees Celsius at 1 atmospheric pressure gas → liquid : condensation : as water vapor is cooled it loses energy causing it to vibrate slower and are brought together forming a liquid liquid → solid : freezing : as liquid is brought below freezing point it loses energy bringing the particles close together , back to the lattice structure of solid ice g g g g g g g g g  Aarav Reddy 1.1.2 describe the structure of the atom, including the nucleus containing protons and neutrons, surrounded by electrons arranged in shells *the first shell holds two electrons , everything after holds 8(octet rule) atoms are the most stable when outermost shell is full atomic number - # of protons of an element 1.1.3 understand that sea water is a mixture of different elements and compounds seawater is a complex mix of chemicals nearly every element on the periodic table is found in the ocean , usually combined with other elements as many different compounds 1.1.4 describe (including through the use of diagrams) the covalent bonding in a water molecule, limited to the sharing of electron pairs between atoms covalent bonds : sharing of electrons between non-metals completing the outermost shells o very strong , as elements with full outer shells are very stable o makes water polar o o emergent properties – characteristics of a compound/molecule that the separate elements do not possess on their own ▪ properties of water  Aarav Reddy 1.1.5 identify (including from diagrams) covalent molecules, including water, carbon dioxide, oxygen, sulfur dioxide and glucose Water – H2O needed for photosynthesis Oxygen – O2 needed for respiration Carbon Dioxide – CO2 needed by plants for photosynthesis Sulfur Dioxide – SO2 needed by bacteria for chemosynthesis Glucose - C6H12O6 produced by photosynthesis  Aarav Reddy 1.1.6 describe (including through the use of diagrams) the ionic bonding in sodium chloride, limited to the loss and gain of electrons to form ions and the subsequent attraction between positive and negative ions ionic bonds – giving and receiving of an electron between atoms o ions then gain a respective charge based on if they lose(-1) or receive(+1) an electron , causing them to be electrically attracted to each other o all salts are made from ionic bonds o 1.1.7 identify (including from diagrams) ionic substances, including sodium chloride and calcium carbonate 1.1.8 state the chemical name and formula of salts found in sea water, including sodium chloride (NaCl), magnesium sulfate (MgSO4) and calcium carbonate (CaCO3) Sodium chloride - NACL Calcium Carbonate – CaCO3 Magnesium Sulfate – MgSO4  Aarav Reddy 1.1.9 explain the formation of hydrogen bonds in water hydrogen bonding – bonding between polar sides of different elements due to the unequal sharing of electrons giving different sides of an element having different charges ; common with water because it’s polar : o more electrons are pulled closer to oxygen --> unequal sharing of electrons : Oxygen is partially – , Hydrogens are partially + o gives ice its hexagonal crystal lattice structure 1.1.10 explain how hydrogen bonding in water affects the properties of water, limited to solvent action, density, and specific heat capacity water is highly soluble : o due to its polarity it can interact with ionic and covalent substances allowing it to break bonds and form new ones density : ice is less dense than water o when water freezes , H-bonds strengthen , forming a crystal lattice structure→ spread farther apart due to symmetrical pattern o how close the water molecules are determine density o ice is less dense than liquid water and can therefore float on it high specific heat capacity : o specific heat capacity : amount of heat needed to raise temp of a unit mass of a given substance by 1 degree Celsius (ability to resist temp change) o water has a high SHC due to such a large number of hydrogen bonds o water acts as a temperature buffer, moderating planet climate 1.2 – Solubility in Water 1.2.1 explain the terms solute, solvent, solution and solubility solute – substance that is capable of being dissolved solvent – substance that is capable of dissolving solution – the mixture of a solute and solvent solubility – how much a solute can be dissolved by a solvent dissolution – the process of being dissolved  Aarav Reddy 1.2.2 describe how soluble salts, such as sodium chloride, dissolve in water by the dissolution of ions water’s polarity allows it to interact with ions , breaking those bonds and forming its own when water dissolves sodium chloride: water breaks down the ionic bond between sodium chloride and forms new bonds (+H bond with Cl- and -O bond with Na+) 1.2.3 explain the effect of water temperature on the solubility of salts as temp ↑ → dissolution rate ↑ o temp increases causes water molecules to move faster helping ions mix with water and interact more frequently , easily breaking ionic bonds o the warmer the water , the saltier 1.2.4 define the term salinity as the concentration of dissolved salts in sea water (note that the unit for salinity used in this syllabus is parts per thousand (ppt)) salinity – concentration of dissolved salts in water o unit is ppt(parts per thousand or ‰) : ▪ amount g of salt left after boiling 1000g of seawater? ▪ average salinity is 35 ppt (salinity varies locally) ▪ hypersaline – water with salinity greater than 40 ppt high evaporation and limited freshwater inflow Don Juan Pond in Antarctica due to lack of precipitation 1.2.5 (PA) investigate the effect of salinity on the freezing point of water salt lowers the freezing point of water because salt molecules block water molecules from coming together and forming hydrogen bonds in a lattice structure it needs to get even colder , meaning water molecules need to vibrate even slower to match each other’s vibration rate and become a solid  Aarav Reddy 1.2.6 explain the effect of surface run-off, precipitation and evaporation on the salinity of sea water precipitation – water that falls from the atmosphere (rain , snow , hail) o lowers salinity by adding more water molecules to dissolve salts evaporation – change from liquid → gas below boiling point o increases salinity by removing water molecules that can dissolve salts run – off : flow of water from land from precipitation o fresh water run – off will lower salinity by adding water molecules that can dissolve salts o saltwater run – off can increase salinity by adding more salts ▪ also, long – distance run off that brings toxic chemicals will alter water salinity and quality 1.2.7 describe the pH scale as a measure of the hydrogen ion concentration in water, including the terms acidic, neutral and alkaline (calculations relating to hydrogen ion concentration are not required) pH – potential of hydrogen pH scale – logarithmic scale (each step 10x the other) measuring concentration of hydrogen ions(H+){ratio of hydrogen to hydroxide ions} o acidic – higher concentration of hydrogen ions [ 7 ]{basic} historically ocean pH has been 8.2 , but now 8.1 due to ↑ greenhouse gas emission (actually 25% rise in acidity due to it being a log scale) 1.2.8 (PA) use litmus indicator, Universal Indicator and pH probes to measure the pH of water samples litmus and universal indicators are usually found as paper strips litmus indicator - determines if acidic or alkaline , but not strength universal indicator – gives color showing the strength or range that then needs to be compared to a color pH scale to estimate a whole number pH probes – produces a precise numerical value  Aarav Reddy 1.2.9 state that oxygen has a low solubility in water oxygen has low solubility since it cannot combine with water molecules o dissolved oxygen(DO) – concentration of dissolved O2 in a solution ▪ as temp and salinity ↑ → DO concentration ↓ ▪ as depth ↑ (temp ↓ , pressure ↑)→ DO concentration ↑ CO2 is very soluble due to it being able to from carbonic acid(weak acid){H2CO3} there’s more carbon dioxide than oxygen in seawater 1.2.10 describe the effect of water temperature, water pressure (depth), atmospheric pressure and salinity on the solubility of gases in water and the implications this has for marine organisms (knowledge of the gas laws is not expected) Factors affecting gas solubility water temperature o temp ↑ → solubility ↓ o colder water dissolves more gas than warmer water: since as temp increase , dissolved gases will evaporate o since its harder for gases to stay in the water , they are less soluble o DO is essential to respiration , meaning temp changes can impact the range of organisms that can live in certain water atmospheric pressure o atmospheric pressure ↑ → solubility ↑ o the pressure increase causes the concentration of gas to increase , pushing gas molecules together , causing them to dissolve o low atmospheric pressure : tropical cyclones , where dissolved gas molecules escape to the atmosphere water pressure due to depth o depth ↑ ( water pressure ↑ )→ solubility ↑ o water pressure increases due to the sheer mass of the water o the pressure forces the gases to stay dissolved salinity o salinity ↑ → solubility ↓ o more solutes mean there’s less space for water molecules to interact and dissolve them o gases are more soluble in freshwater impact of solubility on marine life: gases and organisms intricately connected o CO2 needed for photosynthesis , O2 needed for respiration o N needed for bacterial protein creation dissolved oxygen(DO) – concentration of O2 in a solution o very significant to marine life o oxygen not very soluble in seawater , impacted by: ▪ as temp and salinity ↓ → DO concentration ↑ ▪ as depth ↑(temp ↓ , pressure ↑) → DO concentration ↑  Aarav Reddy o top 100m(surface layer) has greatest DO concentration due to : ▪ motion of water ▪ high photosynthesis from phytoplankton ▪ can reach supersaturation – higher DO in seawater than normal below surface layer , DO concentration changes drastically: oxygen minimum layer – layer(100m-1000m) with lowest DO concentration o due to respiration being performed but lack of photosynthesis o organisms like the vampire squid have adapted due to highly efficient gills or adapted hemoglobin after passing OML , DO increases again due to: o falling detritus already decomposed , less respiration neded o lack of food → reduces need for respiration o as temp ↓ → O2 solubility ↑ o as pressure ↑ → O2 solubility ↑ gases in the atmosphere are in a state of equilibrium with gases in the ocean ( if once increase , the other will too) turbulence – irregular changes in speed and direction in fluid movement o works with wave action to maintain equilibrium o the more turbulence → the easier it is for atmospheric gas to dissolve o leads to higher concentrations of CO2 and O2 in the first 200 meters this is called the photic zone(first 200m that is well sunlit) o water is well mixed due to water and wave action o most photosynthesis occurs here , increasing O2 concentration o 90% marine life found here below is the aphotic zone where its colder due to minimal sunlight , chemosynthesis , nutrient rich o has the OML o and what’s below the OML  Aarav Reddy 1.3 – Density and Pressure 1.3.1 explain how water temperature, water pressure and salinity affect the density of sea water temp ↑ → density ↓ o warmer water is less dense than colder water o warmer water normally near surface , above colder, denser water ▪ between is thermocline – where temp change drastically o *the gradient is less drastic in polar areas since surface water is already likely close to freezing o water doesn’t freeze at the bottom of ocean due to salinity and pressure → as salinity ↑ , freezing point ↓ pressure ↑ → density ↑ o as pressure increases , the molecules are pushed closer together creating more mass in same volume, increasing density o pycnocline – area of rapid pressure change salinity ↑ → density ↑ o fresh water is usually less dense since it has less solutes , floating to top o fresher , less dense water floats on saltier , denser water o halocline – area of drastic salinity change o the saltiest water is usually found at the bottom of the ocean with an exception being tropical areas o in these tropical areas there is high evaporation rates that increase salinity , just below halocline salinity will decrease o in non- tropical areas , halocline will increase in salinity since precipitation is greater than evaporation (less salty surface) 1.3.2 recall and apply the formula: density = mass ÷ volume, with units of kg m–3, kg and m3 respectively mass (kg) density(kg/m3) = ------------------ volume (m3) ***remember the fricking heart 1.3.3 state that the density of ice is lower than sea water, causing ice to float ice is arranged in the lattice structure ; meaning the water molecules are more far apart(due to H-bonds) and are less dense than liquid water → it floats on top  Aarav Reddy 1.3.4 explain the importance of ice floating, limited to its action as a thermal insulator and as a habitat for marine organisms when ice floats , it acts as a thermal insulator (substance that reduces the rate of transfer of thermal energy) reduces the rate of further heat loss from water beneath it this allows water under icebergs and ice sheets to be inhabited by algae and phytoplankton , which are food sources helping the ecosystem polar bears and penguins may also live on top creates a barrier between colder atmosphere and water prevents whole water column from freezing 1.3.5 describe how temperature and salinity gradients form in water columns to produce ocean layers, including the surface layer, thermocline, halocline and deep ocean, and how subsequent mixing of these layers may occur temp and salinity changes with depth form distinct layers in still waters strong winds , wave action , currents can mix these layers o mixing causes thermoclines and haloclines to disappear : summer storms weaken thermocline to disappear until warm weather in spring ships & large animals have virtually no impact compared to weather & currents thermocline – rapid temp change between warmer and colder water halocline – rapid salinity change between fresher and saltier water pycnocline – rapid pressure between 2 layers of different densities around 500 – 1000m for all