Diffusion/Osmosis/Water Potential. Lab. Directions. Read through the background information covered in the next few slides. This is essential knowledge to complete this assignment. Hand write (DO NOT TYPE) your answers to the questions. Be sure to separate questions by section. IE
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DiffusionMolecules are in constant motion and tend to move from regions where they are in higher concentration to regions where they are less concentrated. Diffusion is the net movement of molecules down their concentration gradient. Diffusion can occur in gases, in liquids, or through solids. An example of diffusion in gases occurs when a bottle of perfume is opened at the front of a room. Within minutes people further and further from the source can smell the perfume.
Osmosis is a specialized case of diffusion that involves the passive transport of water. In osmosis water moves through a selectively permeable membrane from a region of its higher concentration to a region of its lower concentration. The membrane selectively allows passage of certain types of molecules while restricting the movement of others.
The solute concentration in the beaker is higher than that in the bag, and thus the water concentration is lower in the beaker than in the bag. This causes water to move from the bag (left) into the beaker (right).
There are often several different types of molecules in a solution. The motion of each type of molecule is random and independent of other molecules in the solution. Each molecule moves down its own concentration gradient, from a region of its high concentration to a region of its low concentration.
Notice that the starch molecules are too large to pass through the pores in the membrane. The iodine molecules move across the membrane in both directions, but their net movement is from the bag, where their concentration is higher, into the beaker, where their concentration is lower. The iodine combines with starch to form a purplish-colored compound.
Types of Solutions Based on Solute Concentration:The terms hypotonic, hypertonic, and isotonic are used to compare solutions relative to their solute concentrations
1 MegaPascal = 10 atm = 145.1 psi
p = pressure potential (outside & inside)
s = solute potential
system = p + s
presults in “+” value
presults in “-” value
- less solute
- more water
- Pure water
- More solute
- less water
****Water will move across a membrane in the direction of the lower water potential****
i = ionization constant: NaCl = 2.0 (Na+ & Cl-)
**for sucrose it will be 1.0 (it doesn’t ionize)
C = Molar concentration
T = Temperature: ° K
R = pressure constant (R = 0.0831 liter bars/mole K)
R will always be the same.
T will be given to you, but must be in ° K.
T = temperature in Kelvin (273 + °C)
A 1.0 M sugar solution @ 22° C under standard atmospheric conditions:
s = -(1)(1.0 mol)(0.0831 L · bar )(295K)
L mol· K
s = -24.22 bars
Part 2, #4.) making the solutions
-(1)(.21)(.0831)(294)= -5.1 bars
a.) Which direction would the water flow? (into the cell)
b.) Which area has a higher water potential? (outside the cell)
c.) What would happen to the concentration of the maltose inside the cell (increase, decrease, remain the same)?