FREEZING POINT DEPRESSION LAB

1)INTRODUCTION: DISCUSS FREEZING POINT DEPRESSION, MOLALITY, COLLIGATIVE PROPERTIES, SOLUTE, SOLVENT.2)DATA,

1) PRESENT A TABLE OF YOUR COOLING CURVE OF LAURIC ACID WITH BHT.

2) PRESENT THE TABLE OF THE NORMAL FREEZING CURVE OF LAURIC ACID (mp about 43 degrees).

3)RESULTS;1) GRAPH ON EXCELL OR OTHER GRAPHING PROGRAM BOTH

COOLING CURVES ON THE SAME GRAPH, USE DIFFERENT COLORS OR LINE PATTERNS FOR EACH CURVE.

2) DISCUSS THE ▲T OF FREEZING.

FREEZING POINT DEPRESSION LAB

MOLALITY(m) = MOLES SOLUTE (BHT IN THIS LAB) Kg of SOLVENT (Lauric Acid)

Find molality by dividing grams of BHT used by

the grams of lauric acid used– (converted to Kg

by dividing by 1000) NOTE. GFM of BHT is

220.0 g/mol

▲TF = kF m

MOLALITYChange in freezing point between pure lauric acid + BHT

(from your data from the two cooling

curves)The freezing point

depression constant, you should calculate this from your data

SOME POINTERS:

1-The ▲ T is the difference between your depressed freezing point of the lauric acid-BHT solution and pure lauric acid which melts at about 43o C.

2- Convert the moles of BHT to moles. Then convert the grams of your lauric acid sample to Kg by dividing by 1000.

3- Solve for Kf.

OBSERVATIONS: list any observations, compare the freezing point of the pure lauric acid to the lauric-BHT solution results verbally.

DISCUSSION AND CONCLUSION. Look up the kf of lauric acid and calculate % error.