Water Notes
water is a universal solvent
Water is the solvent of Life!
Solute – substance dissolved in a solvent to form a solution
Solvent – fluid that dissolves solutes
Example: Ice Tea – water is the solvent and tea and sugar the solutes
In order to raise the temperature of water, the average molecular speed has to increase.
It takes much more energy to raise the temperature of water compared to other solvents because hydrogen bonds hold the water molecules together!
Water has a high heat capacity.
“The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.”
Water is less dense as a solid! This is because the hydrogen bonds are stable in ice – each molecule of water is bound to four of its neighbors. (Solid – water molecules are bonded together – space between fixed
Liquid – water molecules are constantly bonding and rebonding – space is always changing)
Properties of water
Water is the solvent of Life!
Solute – substance dissolved in a solvent to form a solution
Solvent – fluid that dissolves solutes
Example: Ice Tea – water is the solvent and tea and sugar the solutes
- cohesion = water attracted to other water
molecules because of polar properties - adhesion = water attracted to other materials
- surface tension = water is pulled together creating
the smallest surface area possible
In order to raise the temperature of water, the average molecular speed has to increase.
It takes much more energy to raise the temperature of water compared to other solvents because hydrogen bonds hold the water molecules together!
Water has a high heat capacity.
“The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.”
Water is less dense as a solid! This is because the hydrogen bonds are stable in ice – each molecule of water is bound to four of its neighbors. (Solid – water molecules are bonded together – space between fixed
Liquid – water molecules are constantly bonding and rebonding – space is always changing)
Properties of water
- Adhesion
- Cohesion
- Capillary action
- High surface tension
- Holds heat to regulate temperature (High heat capacity)
- Less dense as a solid than a liquid
- Water has high heat capacity, so it can absorb (or release) large quantities of heat without changing temperature
- Moderates coastal temperatures
- salinity = total amount of solid material dissolved in water
- can be determined by measuring water conductivity
- typically expressed in parts per thousand (0/00)
- average seawater salinity = 35%
- main constituents of ocean salinity
- Chloride (Cl-)
- Sodium (Na+)
- Sulfate (SO4 2-)
- Magnesium (Mg2+)
- Processes that decrease seawater salinity:
- Precipitation
- Runoff
- Icebergs melting
- Sea ice melting
- Processes that increase seawater salinity
- Sea ice forming
- Evaporation
- Pattern of surface salinity:
- Lowest in high latitudes
- Highest in the tropics
- Dips at the Equator
- Surface processes help explain pattern
- High latitudes have low surface salinity
- High precipitation and runoff
- Low evaporation
- Tropics have high surface salinity
- High evaporation
- Low precipitation
- Equator has a dip in surface salinity
- High precipitation partially offsets high evaporation
- Factors affecting seawater density:
- Temperature ↑, Density ↓ (inverse relationship)
- Salinity ↑, Density ↑
- Pressure ↑, Density ↑
- Temperature has the greatest influence on surface seawater density
- Lakes, ponds, rivers, and streams…ALL water above ground
- Most urban areas rely on surface water
- Supply resources and allow for travel/trade
- Water that seeps below ground
- Some is taken up and used by plants
- Large amounts found in underground rock formations called aquifers
- Runoff
- Water flowing down slope along Earth’s surface or seep into the ground
- Run off speed determined by slope of the hill
- Ends up in a stream or lake, evaporate, or accumulate into puddles
- seep into ground
- ground must have large enough pores- loose soil
- evaporate
- Certain characteristics will determine whether not water will either seep into or become runoff
- Vegetation
- Vegetation allows for loose soil
- Loose soil allows water to enter ground
- Gardeners do not pack their soil
- Rate of precipitation
- Heavy:
- soil clumps together closing pores
- Fills up ground to quickly and water becomes runoff
- Light:
- allows water to gently slide through
- Less erosion
- Soil Composition
- Effects the waters holding capacity
- Decayed organic matter (humus)
- Creates the pores in soil – Increases retain ability
- Minerals
- Clay – fine mineral which clump together
- Few Spaces
- Sand – large pores
- Slopes
- steep: allows for high runoff and little absorption
- Little: low runoff and high absorption
- Runoff
- Surface water flows in thin sheets and eventually collects in small channels
- Runoff increases, channels widen and become deeper and longer
- Channels fill up again each time with rain
- Channel can become a stream
- Water sheds:
- drainage basin
- Land where all water drains into
- Divide
- High land area that separates watersheds
- All the materials that the stream carries
- Solution
- Material that has been dissolved
- Depends on area where the steam runs through
- Erosion of rocks and dirt
- Suspension
- Small particles held up by the turbulence of stream
- Clay, silt, sand
- Depends on volume and velocity of water
- Bed Load
- Turbulence of water pushes heavy things
- Pebbles and cobbles
- Larger velocity – large objects
- B/c of abrasion, rocks are smooth
- Floods
- Water fills over the sides of a stream banks
- Floodplain: broad flat area of land that extends out from streams for excess flooding
- Slow moving waters
- Low dissolved salt
- Plant and animal life depends on depth of water, rate of flow, and amounts of nutrients, sunlight, and oxygen
- Include lakes, ponds, rivers, and wetlands
- START in mountainous regions
- Cold
- Shallow beds
- Highly oxygenated
- A river’s characteristics changes with geography, climate, and the runoff from nearby developments
Ground Water Notes
Distribution and Movement of Water Underground
- Much of the water in soil seeps downward until it reaches the zone of saturation.
- The zone of saturation is the area where water fills all of the open spaces in sediment and rock.
- Groundwater is the water within this zone.
- The water table is the upper level of the saturation zone of groundwater.
- Movement
- Groundwater moves by twisting and turning through interconnected small openings.
- The groundwater moves more slowly when the
pore spaces are smaller. - Porosity
- the percentage of pore spaces
- determines how much groundwater can be stored
- Permeability
- ability to transmit water through connected pore spaces
- Aquifers are permeable rock layers or sediments that transmits groundwater freely
- Springs
- a spring forms whenever the water table intersects the ground surface
- hot springs
- water is 6-9*C warmer than the mean air temperature of the locality
- water is heated by cooling of igneous rock
- Geysers
- intermittent hot springs
- water turns to steam and erupts
- Wells
- A well is a hole bored into the zone of saturation.
- An artesian well is any formation in which groundwater rises on its own under pressure
- Pumping can cause a drawdown (lowering) of the water table.
- Pumping can form a cone of depression in the water table.
- A well is a hole bored into the zone of saturation.
- Environmental Problems Associated with Groundwater
- Overuse and contamination threatens groundwater supplies in some areas
- treating it as a nonrenewable resouce
- land subsidence caused by its withdrawal
- contamination
- Caverns
- a cavern is a naturally formed underground chamber
- erosion forms most caverns at or below the water table in the zone of saturation
- Taverntine is a form of limestone that is deposited by hot springs of a cave deposit
- Characteristics of features found within caverns
- formed in the zone of aeration
- composed of dripstone
- formed from calcite deposited as dripping water evaporates
- Common features include stalactites (hanging from the ceiling) and stalagmites (growing upward from the floor).
- Karst Topography
- formed by dissolving rocks at, or near, earths surface
- common featured
- Sinkholes- surface depressions
- sinkholes form when bedrock dissolves and caverns collapse
- caves and caverns
- Sinkholes- surface depressions
- Area lacks good surface drainage