Lecture 2- Water Flashcards
What type of environment do cellular functions take place in?
Aqueous
-What is a dipole moment?
-What is a dipole moment determined by? (2 things)
-O2 is more electronegative/net negative charge
-Hydrogens have net positive charge
-Dipole moment is determined by the magnitude of the charges AND the distance between them
What is a covalent bond?
-Sharing of electrons
-In water H+ bonds with O2-
What is hydrogen bonding?
Electrostatic connection between a polar molecule (water) and a small electronegative atom (oxygen)
Hydrophilic properties
Charged and polar
Positive and negative charges attract
Hydrophobic properties
Uncharged and non-polar
Share electrons equally
Amphipathic properties
Experience hydrophilic and hydrophobic regions
Why do some hydrophilic molecules not dissolve into ions in water like NaCl does?
Water can disrupt hydrogen bonds between molecules like sucrose which makes them break into smaller pieces of the same molecule rather than ions
How does the structure of triglycerides affect its interaction with water?
Triglycerides are non-polar so they cannot break water’s hydrogen bonding to dissolve/mix together. Oil (a fat) will separate from water do to being uncharged
In amphipathic interactions, how do polar and non-polar regions interact with a polar molecule like water?
-Polar regions interact with the polar molecule
-Non-polar regions will interact with each other
How would amphipathic properties play a role in soap, water, and grease?
-Soap molecules make the surface of grease particles charged.
-Soap molecules repel each other and interact with water
Why are water molecules at the surface compressed tightly together?
Surface molecules experience sideward and downward intermolecular forces. Whereas under the surface, molecules move in all directions and/in random motion due to kinetic energy.
What does the hydrogen bonds between water molecules form?
What does this produce?
Lattice of water molecules
Surface tension
What does the kinetic energy (heat) used on water molecules break?
Hydrogen bonds
Why does ice float on the surface?
Water as a solid is less compact/dense than water as a liquid
The crystallized structure of ice is well organized.
How do molecules or ions in a solution move during diffusion?
From high to low concentration regions
How long will diffusion proceed?
Until the molecules are evenly distributed and equilibrium is reached
How much solute would be required for a 100 mM solution of sodium chloride?
100n mM NaCl yields 100 mmoles of Na+ ions and 100 mmoles of Cl- ions
200 millimolar solution
100+100 (solvent)=200 (solute)
What is osmosis?
Water moving from high to low concentration regions through a selectively water permeable membrane
How can osmosis be used to balance pressures?
Hydrostatic pressure can offset osmotic pressure
What is equilibrium defined by?
The point where the probability of ions moving from left to right is the same as the probability of ions moving from right to left
How are atoms in water molecules linked?
Covalent bonds
How are intermolecular forces linked?
Hydrogen bonds
What 2 properties can disrupt hydrogen bonding?
Amphipathic interaction and heat
What 2 ways can equilibrium in a solution be reached?
Diffusion and osmosis
What attributes in water give it a high boiling point?
Intermolecular forces are stronger and harder to break
15 millimolar NaCl (on the left) and 30 millimolar urea (on the right) are separated by a membrane that is permeable ONLY to water. Which of the following can occur?
Water will not flow
Water will flow right to left
Water will flow left to right
None of the above
Water will not flow
15 NaCl in water breaks into 15 Na+ ions and 15 Cl- ions=30 total
30=30 so water will not flow
Which of the following are responsible for hydrophobicity?
Charged particles
Polar particles
Non-polar partciles
More than one answer is correct
Non-polar partciles
Atoms in water molecules are linked by _________?
Hydrogen bonds
Covalent bonds
Dipole moments
Ionic bonds
Covalent bonds
Water is liquid at room temperature because
-Hydrophobic bonds keep the water molecules together
-Water molecules are uncharged
-Hydrogen bonds form between the hydrogen atom on the neighboring water molecule to hold the water molecules together
-Hydrogen bonds form between the hydrogen atom on one water molecule and the oxygen atom on a neighboring water molecule
-None of the above are correct
Hydrogen bonds form between the hydrogen atom on one water molecule and the oxygen atom on a neighboring water molecule
What contributes to the surface tension in water?
-Water molecules move in ALL directions under the surface
-Water molecules move sidewards and downwards on the surface
-Water molecules are in a constant state of motion
