1) This is a thermodynamics questions
In your body, normal osmolarity of blood serum is just under 0.3 molar. Because cell membranes are permeable to water, the osmolarity of intracellular fluid is approximately equal to that of extracellular fluid (though the intracellular and extracellular composition in terms of specific ions and proteins is quite different). As an aside, measurement of osmolarity of serum is an important clinical test used to check for dehydration or other imbalances of water and electrolytes.
a) In the supplemental information, the osmosis example presented involves sucrose as a solute, but the van't Hoff equation also applies for other solutes. Using this formula (â = cRT, where â is the excess pressure), calculate the osmotic pressure associated with 0.3 molar concentration of osmolytic particles (e.g., ions, proteins, or other dissolved particles) in contact with pure water through a semi-permeable membrane at physiological temperature of 310 K. Express your results in atmospheres of pressure (1 atmosphere of pressure is 1.0x105 Pascal, where 1 Pascal is a Newton/m2).
b) A biological cell membrane is a bilayer of phospholipid molecules, only a few nanometers thick, and can basically be thought of much like a soap bubble, except immersed in aqueous solution. If cells are placed in pure water, they often swell and burst in just a few minutes. Explain why this would happen.
1) This is a thermodynamics questions
In your body, normal osmolarity of blood serum is just under 0.3 molar. Because cell membranes are permeable to water, the osmolarity of intracellular fluid is approximately equal to that of extracellular fluid (though the intracellular and extracellular composition in terms of specific ions and proteins is quite different). As an aside, measurement of osmolarity of serum is an important clinical test used to check for dehydration or other imbalances of water and electrolytes.
a) In the supplemental information, the osmosis example presented involves sucrose as a solute, but the van't Hoff equation also applies for other solutes. Using this formula (â = cRT, where â is the excess pressure), calculate the osmotic pressure associated with 0.3 molar concentration of osmolytic particles (e.g., ions, proteins, or other dissolved particles) in contact with pure water through a semi-permeable membrane at physiological temperature of 310 K. Express your results in atmospheres of pressure (1 atmosphere of pressure is 1.0x105 Pascal, where 1 Pascal is a Newton/m2).
b) A biological cell membrane is a bilayer of phospholipid molecules, only a few nanometers thick, and can basically be thought of much like a soap bubble, except immersed in aqueous solution. If cells are placed in pure water, they often swell and burst in just a few minutes. Explain why this would happen.
