D2.3 water potential Flashcards
why is water known as a universal solvent
because of its ability to dissolve so many other molecules
explain the structure of water
one water molecule;
2 hydrogen atoms covalently bonded to one oxygen atom
oxygen more elctronegative pulls shared pair of electron closer to oxygen, resulting in lsight negative charge of oxygen and slight pos in hydrogen so water is a dipole molecule
why do hydrogen bonds form between water molecules
due to the weak electrostatic attraction between the slight positive charged hydrogen atom of one water molecule and slight negative charged oxygen atom of another water molecule
Large networks of hydrogen atoms result in
unique properties of water, such as its high specific heat capacity
what determines whether water has the ability to dissolve a substance
if force of attraction between oppositely charged ions is weaker than the force of attraction between ions and water, water can dissolve the substance
what happens when a slight ionic compound is added to water
slight pos charge of hydrogen attracted to neg ions and vice versa
water molecules surround ions forming hydration shells this leads to separate of solute particles and their uniform distribution throughout the solution= dissolution
how do covalent compounds dissolve in water
forming intermolecular interactions with the dipolar water molecules
hypertonic
A solution that has a higher solute concentration than another solution.
hypotonic
A solution that has a lower solute concentration than another solution.
isotonic
A solution that has the same solute concentration as another solution.
osmosis
The movement of water molecules across a semi-permeable membrane from a high to low concentration.
what happens if a cell is placed in a hypertonic solution
net movement of water out of the cell into the solution, cell shrinks
plant cell- plasmolysis
animal cell- crenated
what happens if a cell is placed in a hypotonic solution
net movement of water into the cell, cell swells
plant cell-turgid due to high tugor pressure
animal cell- lysed, may burst
what happens if a cell is placed in a isotonic solution
no changes to volume of cell
plant cell- flaccid
animal cell- normal
what does a high stdev indicate
higher variability in the data set
standard error
a measure of the variability (spread) between multiple data sets. This can be used to determine how precise the data are, where a data set with a low standard error has a higher precision than a data set with a high standard error
plasmolysis
The shrinking of the cell membrane away from the cell wall in plant cells due to a loss of water from the cell.
what are medical applications of isotonic solutions
organs/ tissues used for transplantation preserved in a special solution, provide optimal solutions protect organ or tissue agaisnt damage, provide organ with necessary nutrients and oxygen to prevent loss or gain of water, increases likelyhood of succesful transplantation
isotonic solutions may be given intravenously (through vein), allows rapid and direct absorption of medications, fluids or nutrients into the circulatory system, bypassing the digestive system
what is water potential
A measure of the potential energy of water, resulting from the solute potential and pressure potential at standard conditions
1 bar equal to
100kPa
Pure water in standard conditions has a water potential of
0kPa
highest possible water potential
As water potential becomes more negative
it becomes harder for water to move
how is the water potential measured
solute potential + pressure potential
what is solute potential
attraction of water molecules to solute particles, which, when present, reduces the number of free water molecules and limits the movement of water.
pressure potential
the physical pressure exerted on a system. Pressure potential can be positive and is exerted outwards from a cell or negative
Positive pressure potential increases water potential and negative pressure potential decreases water potential.
what happens when a cell is placed in a hypotonic solution in terms of solute potential
solute potential of tissue is more negative than the solute potential of the solution
as a result water moves into the cell from area of less neg solute potential to more neg solute potential to equilibrate the solute potentials
additional water causes them to apply an extra pressure outwards inside the cell= tugor pressure as a result pressure potential is positive because pressure inside the cell is bigger than pressure outside
