Chapter 3 Flashcards
What is the main reason the earth is habitable?
Abundance of water
The water molecule is a ______ molecule
polar
Cohesion
Water molecules hold together by hydrogen bonds
Adhesion
Attraction of different substances
What are water’s properties that facilitate an environment for life?
- Cohesive behavior
- Ability to moderate temperature
- Expansion upon freezing
- Versatility as a solvent
Surface tension is related to which property of water?
Cohesion
Because of its high specific heat capacity, water _______ from ______ and ________ to _________
- absorbs heat from warmer air
- releases stored heat to cooler air
Kinetic energy
The energy of motion
How do atoms and molecules have kinetic energy?
Atoms are always moving
Faster moving atoms = more _____
kinetic energy
Total kinetic energy due to movement of atoms is _____
heat
Because of kinetic energy, head depends partially on _____
volume
Coffee has >______ than a pool, but a pool has >_____
temperature
heat
Calorie
Amount of heat required to raise the temperature of 1g of water by 1 degree
Specific heat
Amount of heat that must be absorbed or lost for 1g of that substance to change temperature by 1 Celsius
Specific heat of water
1 cal/g/C
Specific heat can also be described as…
How well a substance resists temperature change when absorbing/releasing heat
Heat is absorbed when ________, and released when hydrogen bonds _____
- hydrogen bonds break
- hydrogen bonds form
Why is specific heat good for life on earth?
Minimizes temperature fluctuations to limits that permit life
Evaporation
Transformation from liquid to gas
Heat of vaporization
Heat a liquid must absorb for 1 g to be converted to gas
Evaporative cooling
Liquid evaporates, cooling surface
Why does ice float in water?
Hydrogen bonds are more ordered, making ice less dense
Why does ice have less kinetic energy?
Atoms more ordered to cause less movement
What would happen if ice sank?
All bodies of water would eventually freeze solid
Solution
Mixture of 2+ substances
Solvent
Dissolving agent of solution
Solute
Substance that is dissolved
Aqueous solution
Solution in which water is the solvent
Hydration shell
Sphere of water molecules around dissolved ions from ionic compounds
Why is water a versatile solvent?
Its polarity allows it to form hydrogen bonds easily
Apart from ionic compounds, water can also dissolve compounds of __________
nonionic polar molecules
A large polar molecule like protein can dissolve in water if it has what?
Ionic and polar regions
Hydrophilic
Has an affinity for water
Hydrophobic
Does not have an affinity for water
Oil molecules are (hydrophobic/hydrophilic) because…
Hydrophobic because they have relatively nonpolar bonds
Colloid
Stable suspension of fine particles in liquid
What do chemical reactions depend on? Therefore, this depends on…
Collisions of molecules and therefore on the concentration of solutes in an aqueous solution
Molarity
Number of moles of solute per liter of solution
When hydrogen shifts atoms in hydrogen bond, what happens?
- Hydrogen atom leaves electron behind and transferred only as hydrogen ion
- Molecule w/ extra proton is hydronium ion
- Molecule w/ lost proton is hydroxide ion
A _____ increases the H+ concentration of a solution, while a _______ reduces the H+ concentration
- acid
- base
Buffers
Substances that minimize changes in concentration
