2.2 Water Flashcards
What is the structure of water?
Two hydrogen bonds covalently bonded to an oxygen atom. H2O.
What makes water polar?
Oxygen has a higher electronegativity, causing electrons be closer to it; there is a slight charge difference across the molecule’s poles.
How does water create hydrogen bonds?
It is dipolar; the hydrogens bond with the oxygen and vice versa.
What are the properties of water?
CAST
Cohesive—water molecules will stick to each other
Adhesive—water will stick to charge substances/surfaces
Solvent—polar and ionic substances are soluable in water (ex. amino acids, sugars)
Thermal—water can absorb a lot before its hydrogen bonds break and it changes state
How is water’s thermal properties used in homeostasis?
Evaporation of water becomes sweat and helps our body cool down. The energy for this process comes from the heat of our skin. Its high specific heat capacity allows it to absorb thermal energy before it evaporates.
Why does water have a high surface tension?
The hydrogen bonds are strong and allow water to resist low levels of external force. It also allows water bugs to walk on water!
Why is water the universal solvent?
It can dissolve any substances that contain ions (charged particles) or polar molecules (electronegative atoms) because the polarity of water can weaken ionic bonds.
What is a hydrophilic substance?
Substances that freely dissolve in water, such as polar molecules and ions.
What is a hydrophobic substance?
Substances that do not freely dissolve in water, such as fats and oils (large and non-polar molecules).
Give examples of water soluable substances.
NaCl—ionic compound
Glucose—many hydroxyl groups
Amino acids—transported in an ionized state
Oxygen—in low amts only; large amts usually have to be carried by hemoglobin in red blood cells
Cholesterol—slightly; they are transported through blood with lipoproteins that have a amphipathic surface
Give examples of water insoluable substances.
Lipids—non-polar and hydrophobic
Hydrophobic portions of proteins are faced inward while the hydrophilic portions “shield” them
