Chapter 3: Water and Life Flashcards
What is cohesion? Why is it important?
Water’s ability to bind to itself with multiple hydrogen bonds, resulting in properties like surface tension due to it’s stronger structure.
What is kinetic energy? How does it relate to thermal energy?
Kinetic energy is the energy of motion. The kinetic energy associated w the random movement of atoms or molecules is thermal energy.
What does temperature represent in terms of kinetic energy? How does it differ from thermal energy?
average kinetic energy of molecules in a body of matter, regardless of volume. In contrast, thermal energy is the total kinetic energy, depends on volume.
Thermal energy in transfer from one body of matter to another is defined as
heat
What is specific heat? Why is water’s high specific heat important?
The specific heat of a substance is defined as the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C
water will change its temperature less than other liquids when it absorbs or loses a given amount of heat.
A large body of water can absorb and store a huge amount of heat from the sun in the daytime and during summer while warming up only a few degrees.
Why does water have such a high specific heat?
Hydrogen bonding
Heat must be absorbed in order to break hydrogen bonds; by the same token, heat is released when hydrogen bonds form. A calorie
of heat causes a relatively small change in the temperature of water because much of the heat is used to disrupt hydrogen bonds before the water molecules can begin moving faster.
What is evaporative cooling?
As a liquid evaporates, the surface of the liquid that remains behind cools down (its temperature decreases). This evaporative cooling occurs because the “hottest” molecules, those with the greatest kinetic energy, are the most likely to leave as gas
Why do water molecules expand when they become solids?
Hydrogen bonding. When water cools, its molecules move too slowly to break hydrogen bonds and become locked in crystal lattice. In contrast, in liquid water these hydrogen bonds are constantly breaking and reforming
What is a hydration shell?
sphere of water molecules around a broken compound. If a compound has ionic and polar regions on its surface, it can be broken down by water.
Hydrophobic substances are ___ and ____
non ionic and non polar
Most buffer solutions contain a ___ acid and its corresponding base, which combine
reversibly with hydrogen ions
Most buffer solutions contain a weak acid and its corresponding base, which combine
reversibly with hydrogen ions
