Water Flashcards
H2O ionization products
H+ and OH-
Structure of the water molecule
Tetrahedron(ish)
2O (+)
H (2-)
Hydrogen bonds cause
- Different electronegativity of atoms
- Unequal electron sharing in the H-O bonds
- Electric dipoles in the H-O bonds
- Dipole moment in the water molecule
- Hydrogen bond btween H and another molecule’s O (weak interaction)
Hydrogen bonds characteristics
- Each H2O can form hydrogen bonds with four neighboring molecules
- Lifetime of a h bond 10-12 seconds, nez one forms in 0,1 ps
- H bonds are responsible for the cohesion of liquid water and some water properties
Physicochemical properties of water
- Thermal regulator
- Osmotic controller
- Universal solvent and solute transporter
- Cohesive and adhesive nature
Temperature dependent property of water
Increasing number of hydrogen bonds with the change of state
Density of water
Maximum density at 3,98 C
only common substance less dense in solid form than in liquid form
Cohesive forces and surface tension
The cohesive nature of water gives it surface tension, at liquid-air interfaces, water molecules attract to each other more than to the molecules in the air (due to adhesion)
Adhesive forces and surface tension
Adhesion forces are the forces that attract water molecules to diferent polar molecules in a surface or physical support
Capillarity
The ability of a liquid to flow in narrow spaces through polar surfaces, such as glass, without the assistance of external forces, and in opposition to gravity.
Termal regulator
Water has high heat of vaporisation, fusion and capacity, therefore its temperature remains relatively stable
Universal solvent
SOLUBILITY is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in the solvent to form a homogeneous solution.
Polar charged molecules solubility
Polar charged molecules are more easily dissolvable in water because of their property to replace normal hydrogen bonding by a more energetically favorable hydrogen bond.
Polar uncharged molecules solubility
Polar uncharged biomolecules dissolve more easily because of the stabilizing effect of the bond between hydroxyl or carbonyl sugar group and the polar water molecule
Polar molecules solubility
As the number of Carbon in an alcohol or amine increases, the solubility in water decreases, but the solubility in organic solvents increases
Non polar molecules solubility
Nonpolar biomolecules are HYDROPHOBIC interfere with water-water interactions but are unable to form water-solute interactions
Amphipathic molecules solubility
Polar regions maximized to have an interaction with water and non polar regions cluster together to minimize the hydrophobic area
Ionic compounds solubility
Water dissolves salts by HYDRATING them: weakening the electrostatic interactions between ions and stabilizing interactions with water molecules. The salts dissolved into ions are electrolytes.
