A1.1 Water Flashcards
define cohesion
molecules of the same type(water) are attracted to each other
define surface tension
due to cohesion between water molecules and those immediately next to and below them. Must be broken so an object can enter the water from above
define adhesion
attraction between 2 different types of molecule(water and another polar molecule) due to hydrogen bonding
define capillary action
movement of a liquid(water) upwards against gravity within a narrow tube. Due to adhesion between water molecules and the inner wall of the tube, and cohesion pulling more water molecules up with them
explain how hydrogen bonds form in water(4)
1) water molecules are polar
2) because of the unequal sharing of electrons between hydrogen and oxygen(oxygen is more electronegative)
3) attraction between positive and negative
4) hydrogen bond formed between hydrogen and oxygen of different water molecules
define hydrophilic
‘water-loving’ molecules that are attracted to or can dissolve in water
define hydrophobic
‘water-fearing’, non-polar molecules that aren’t attracted to or can’t dissolve in water
give 1 way hydrophobic substances are important
the waxy cuticle of plant leaves is hydrophobic to prevent the leaf losing too much water by evaporation
define viscosity
a fluid’s resistance to flow, or resistance to an object moving through it
define thermal conductivity
the ability of a substance to transfer heat
define SHC
the energy in Joules required to raise the temperature of 1kg of a substance by 1 degree celsius
define buoyancy
ability of solids to float in fluids if their density is lower
what is a medium?
something in which processes can occur
what did the first living cells originate in?
aqueous solutions ‘primeval soup’
what are the 8 life processes?
metabolism, nutrition, growth, reproduction, movement, response to stimuli, excretion, homeostasis
what is intramolecular in terms of hydrogen bonds?
the 2 bonds between oxygen and hydrogen atoms in a water molecule
seal’s buoyancy properties in water
density is close to seawater’s so it can float easily
loon’s buoyancy properties in water
loon’s density is much higher than air’s so it beats its wings to stay airborne
seal’s/loon’s viscosity properties in water
seal has to overcome much more resistance when it swims through water than the loon when it flies in air bc water has high viscosity due to hydrogen bonding
loon/seal’s SHC in water
it takes more heat to raise the temp of water by a degree than air because water is more dense, so water heats up and cools down more slowly than air. so water habitats are more thermally stable
how did water arrive on earth?
at first, water would have boiled and been lost so the water that is now on earth must have arrived later when the earth had cooled down so it could remain liquid and be retained
what is the main hypothesis about how water came?
it was brought when asteroids with ice collided with the early earth, water melted adding to the volume of liquid water in oceans
which 2 factors allow retention of water in a liquid state on earth?
strong gravitational pull bc of earth’s size; intensity of sunlight due to distance from the sun keeps earth below 100 degrees and mostly above 0
what is the Goldilocks zone?
the range of distances from a star that keep temps between 0 degrees and 100 degrees; position of earth in relation to the sun
