Osmosis

Question 1

Define the terms osmosis and osmolarity

Answer 1

Osmosis: net diffusion of water across a membrane.
Osmolarity: measurement of the number of solute particles within a solution

Question 2

Know how to calculate osmolarity of a solution.

Answer 2

You calculate the osmolarity by taking the molarity of the solution and multiplying it by the number of ions it will dissociate into the # of solute particles formed by solute molecule x molarity (M)
Ex: .15M NaCl = .15 x 2 (Na+ and Cl-) = .3 Osmoles or 300 mOsmoles

Question 3

How do you determine tonicity – hypertonic, isotonic, hypotonic after osmolarity has been calculated or given to you? Understand the role of the non-penetrating solute and how it influences osmosis.

Answer 3

Tonicity is ability to change shape of cells by altering water volume, it’s the affect osmolarity has on a cell membrane. In a penetrable solution it will always be hypotonic but if it’s non-penetrating then it will either be isotonic, hypotonic, or hypertonic depending on the osmolarity

Question 4

What happens to a cell when placed in hypertonic, isotonic and hypotonic solutions?

Answer 4

Isotonic: cell stays the same shape
Hypertonic: cell shrinks
Hypotonic: cell swells/lyses