2.10-2.16 Flashcards
Where do water’s life-supporting properties come from?
the structure and interaction of its molecules (polarity and resulting hydrogen bonds)
How long do hydrogen bonds between molecules last?
trillionth of a second
What is the property of water that comes from hydrogen bonding?
Cohesion/surface tension. It is much stronger in water than many other liquids.
How does the cohesion of water supports tree life?
When water evaporates, it pulls on the water to come up. Without cohesion, those particles would not come up together.
How does adhesion play a role in how water supports tree life?
Water adheres itself to cell walls when traveling up through plants veins, which counteracts gravity.
Define surface tension. What is water’s surface tension like?
measure of how difficult it is to stretch or break the surface of a liquid. Hydrogen bonds=unusually high surface tension.
What is the classic example of water’s surface tension/cohesion?
the meniscus of an overfilled glass of water.
What creates beads of sweat?
The cohesion and surface tension of water.
Define thermal energy
kinetic (random movement) of atoms and molecules.
Define heat
thermal energy in transfer from a warmer to a cooler body.
Define temperature
the intensity of the heat or the average kinetic energy of the particles
Define specific heat
the amount of heat needed to raise the temperature of 1 gram of a substance 1 degree Celsius (°C).
Why does it take so long for water to heat up?
Because of hydrogen bonding; very high specific heat.
To increase the thermal energy of water, what process must it undergo?
To make water particles move faster, hydrogen bonds must be broken. When they are broken, they release heat and allow for thermal energy to increase. Water absorbs much heat while only heating up slightly.
What happens when water cools?
hydrogen bonds are reformed; water releases immense amounts of heat
What role do oceans, lakes and rivers play in regulation of the earth’s temperature?
They absorb and store much of the heat from the sun during hotter areas. They give off heat gradually.
Why are coastal areas’ temperatures more mild?
because more heat is stored and let off slowly by body of water.
What role do oceans, lakes and rivers play in temperature and marine life? in you?
Because of its high specific heat, marine life is able to flourish. Humans are made 66% of water, and it is key for homeostasis.
Define evaporative cooling.
occurs because the molecules with the greatest energy leave. When a substance evaporates, the surface of the liquid that reminds behind cools down.
Why is evaporative cooling important.
helps terrestrial organisms from overheating (sweating, ex.), leaves becoming too dry, cools tropical sea by evaporation of surface water.
Explain the popular adage, “it’s not the heat, it’s the humidity”
High humidity hampers cooling by slowing the evaporation of sweat.
Why is ice less dense than liquid water?
Hydrogen bonds; they crystalize/lattice themselves to be the same (further) distance away from other molecules.
If ice sunk, what would happen to life?
ponds, lakes and oceans would freeze solid. But ice actually acts as an insulator for the warmer water below in cool temperatures.
Explain how freezing water can crack boulders.
Water in the crevices of a boulder expands as it freezes because the water molecules become spaced farther apart, in forming crystal ice.
