Match each solution to the correct osmolarity.

Question

1.   Match each solution to the correct osmolarity.

          -     A.     B.     C.     D.      

1.0 M glucose

         -     A.     B.     C.     D.      

1.0 M NaCl

         -     A.     B.     C.     D.      

2.0 M NaCl

         -     A.     B.     C.     D.      

1.0 M CaCl2

         -     A.     B.     C.     D.      

0.50 M Na3PO4

A.)

1.0 osmol

B.)

2.0 osmol

C.)

3.0 osmol

D.)

4.0 osmol

Answer 1

1.0 M glucose = 1.0 Osmol (A)

1.0 M NaCl = 2.0 Osmol (B)

2.0 M NaCl = 4.0 Osmol (D)

1.0 M CaCl2 = 3.0 Osmol (C)

0.50 M Na3PO4 = 2.0 Osmol (B)

The way you determine the osmolarity is to dissociate the compound, if it does in fact dissociate in water, and count the number of particles present. Multiply this by the original molarity to get osmolarity. So, for glucose, it does NOT dissociate so number of particles is one. CaCl2 dissociates into 1 Ca ion and 2 Cl ions, for a total of 3 particles, etc.