Osmosis Flashcards
Regarding osmosis (true or false):
Osmosis is a process in which a solvent moves across a semi-permeable membrane from a hypertonic solution to a hypotonic solution
False. Osmosis is the process in which a solvent moves across a semi-permeable membrane from a hypotonic solution to a hypertonic solution.
Regarding osmosis (true or false):
Erythrocytes exposed to a hypotonic solution take up water and swell
True
Regarding osmosis (true or false):
A semi-permeable membrane is defined as a membrane permeable to solute but not to solvent
False. A semi-permeable membrane is permeable to solvent but not to solute.
Regarding osmosis (true or false):
Erythrocytes exposed to an isotonic environment neither take up nor lose water
False. Erythrocytes in an isotonic environment both take up and lose water in equal measure. The net water content of the erythrocyte remains constant.
Regarding osmosis (true or false):
Slugs thrive on a diet of table salt
False. Slugs shrivel and die as their water content is lost to the powerfully hypertonic salt environment.
Regarding the van ‘t Hoff equation, where π = osmotic pressure:
A. π = iMR/T
B. π = iMT/R
C. The equation takes no account of the nature of the solutes within the solution
D. π = iTR/M
E. 22.4 litres of a 1 molar solution at 0°C exerts 1 atmosphere of osmotic pressure
C. Correct.
A. Incorrect. The elements in the van ‘t Hoff equation multiply to produce a figure for π (pressure).
B. Incorrect. See A.
D. Incorrect. See A.
E. Incorrect. van ‘t Hoff explains that where:
the temperature is 0°C (273.15 K), and
22.4 litres of solution contains 1 mole of solute
then the osmotic pressure is 101.325 kPa, equivalent to 1 atmosphere (1 bar).
A 1 molar solution is not the same as a solution containing 1 mole of solute. 22.4 litres of a 1 molar solution would exert 22.4 atmospheres of osmotic pressure.
Regarding colligative properties (true or false):
Colligative properties include freezing point elevation and boiling point depression
False. Freezing points are lowered and boiling points raised due to the colligative properties of solutes.
Regarding colligative properties (true or false):
Osmotic pressure is a colligative property
True
Regarding colligative properties (true or false):
Colligative properties are employed in an osmometer
True. An osmometer may measure the osmotic pressure of a solution indirectly by measuring the temperature at which it freezes.
Regarding colligative properties (true or false):
Colligative properties are influenced by the nature of the solute as well as the number of osmotically-charged particles
False. Colligative properties are completely independent of the nature of the solute in a solution.
Regarding colligative properties (true or false):
Dissolved molecules alter the physical properties of solutions
True. The osmotic activity of dissolved molecules alters the physical property of a solution.
Regarding osmolarity and osmolality (true or false):
Both osmolarity and osmolality describe the number of osmoles in a solution
True. Osmolarity, spelt with an r, is a measure of the number of osmoles per litre of solution, and osmolality, spelt with an l, is the number of osmoles per kilogram of solution.
Regarding osmolarity and osmolality (true or false):
Osmolarity is the preferred measure of osmotic activity as its calibration to the kilogram enables quick and accurate calculations
False. Osmolality is the preferred term because the volume of solution alters with temperature. This means that a solution changes osmolarity, but not osmolality, as temperature varies.
Regarding osmolarity and osmolality (true or false):
Two moles of glucose gives as many osmoles as two moles of NaCl
False. Every mole of NaCl gives two osmoles, twice as many as a mole of glucose.
Regarding osmolarity and osmolality (true or false):
Salts in solution are assumed to have separated out into their component ions
True
