Refining Technology Workbook

EXPERIMENT 01

Object:

To determine the Melting Point of petroleum Wax by Cooling Curve Method (ASTM D87)

Apparatus:

Test Tube, Water Bath & Thermometer

Theory:

Melting point (cooling curve) of petroleum wax: The temperature at which melted petroleum wax first shows a minimum rate of temperature change when allowed to cool under prescribed conditions.

Melting point (cooling curve) is a test that is widely used by wax suppliers and consumers. It is particularly applied to petroleum waxes that are rather highly paraffinic or crystalline in nature. The test is particularly applicable to substances that are rather highly paraffinic or crystalline in nature.

Procedure:

Fill the water bath with water at a temperature of 16 to 28°C. The bath temperature is kept within these limits throughout the test. Heat the wax sample at which the wax is completely molten Insert the melting point thermometer through the center of a cork. Read the melting point thermometer for every 30 s. Observe the progress of these sequential readings to determine the appearance of the plateau. Identify the plateau as the first five consecutive readings.

Observation:

S. No.Time (sec)

Temperature °C

1 0 832 30 773 60 704 90 645 120 61.56 150 597 180 598 210 599 240 59

10 270 5511 300 5212 330 48

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0 50 100 150 200 250 300 3500

10

20

30

40

50

60

70

80

90

Cooling Curve

Temperature

Time (Sec)

Tem

pera

ture

°C

Result:

Melting point of given Petroleum Wax is found to be 59 °C.

Refining Technology Workbook

The homogenous part of a heterogeneous system separated by a distinguishable boundary is known as a phase. A phase of matter is uniform with respect to its physical and chemical properties. Matter undergoes phase transitions to change from one phase to another. The primary phases of matter are solids, liquids, gases.

The distinct forms the matter in different phases can take are considered as a state of matter. Three classic states of matter are solid, liquid and gas. Matter changes state depending on their internal energy level and the temperature, which is an indicator of the internal energy.

Phase diagrams plot pressure (typically in atmospheres) versus temperature (typically in degrees Celsius or Kelvin). The labels on the graph represent the stable states of a system in equilibrium. The lines represent the combinations of pressures and temperatures at which two phases can exist in equilibrium, these lines define phase change points. The line which divides the solid and gas phases represents sublimation (solid to gas) and deposition (gas to solid). The line which divides the solid and liquid phases represents melting (solid to liquid) and freezing (liquid to solid). The line which divides the liquid and gas phases represents vaporization (liquid to gas) and condensation (gas to liquid). There are also two

Refining Technology Workbook

important points on the diagram, the triple point and the critical point. The triple point represents the combination of pressure and temperature that facilitates all phases of matter to co-exist. The critical point is the point on a phase diagram at which the substance is indistinguishable between liquid and gaseous states.

Heat of fusion is the heat required by the body to change its state from solid to liquid. Heat of vaporization is the heat required by the body to change the temperature from liquid to gas. The temperature during a phase change is constant because the energy supplied to the matter during phase change is used to overcome the attractive forces between molecules rather than increasing the kinetic energy.