Problem set: water and solute movement across membranes

22.

Answer the questions below based on the following solution:

You have 200 ml of a 25 % MgCl2 solution

(MW Mg = 24.3, Cl = 35.5)

(Each mole of MgCl2= 3 osmoles in solution)

Show your work.

a.

Since this is a 25% solution, how many grams of MgCl2 are in 100 ml of the solution?

b.

How many grams total are in the 200 ml?

c.

How many grams does 1 mole of MgCl2 weigh?

d.

How many moles are in the 200 ml MgCl2solution?

e.

How many osmoles are in the 200 ml MgCl2solution?

f.

What is the osmolarity of the MgCl2 solution?

g.

Cell membranes are impermeable to Cl- ions. What would the tonicity of this solution be if introduced to the ECF?

23.

In the diagram below are two solutions (A and B) separated by a membrane permeable to water but not solutes. Use this as the starting condition for the questions below. (10 pts)

B.

659 osmoles

9 liters

A.

540 osmoles

10 liters

a.

In this initial condition, what is the osmolarity of solution A?

In this initial condition, what is the osmolarity of solution B?

b.

If you compare osmolarities of solution A to B, solution A is _______________ to B.

c.

In which direction will water move between these compartments?

d.

After all osmosis has occurred, what will the osmolarity of compartment A be?

e.

How much total water has moved into or out of compartment A?