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Melting Point of Ice
The constant temperature at which a solid changes to a liquid is called the Melting
Point of the solid. At the melting point the solid and liquid phases exist in equilibrium.
For a given substance, the melting point of its solid form is the same as the freezing
point of its liquid form, and depends on factors such as the purity of the substance and the
surrounding pressure. For ice the melting point is 0°C or 273K. The chemical element
with the highest melting point is tungsten (3410°C), which is used for making filaments
in light bulbs. The aim of this experiment is to determine
the melting point of ice.
Materials Required:
Ice cubes, 250 ml beaker, thermometer suspended in a stand, glass rod and a heating mantle
which is used to control temperature and to get uniform heating.
Procedure:
First suspend a thermometer using a clamp stand so that its bulb is at the center of
the beaker which is placed inside the heating mantle.
Take some ice cubes and put them quickly in a beaker.
Start heating the ice cubes by increasing the temperature of the heating mantle.
Now stir the ice cubes continuously using a glass rod and note the initial temperature,
t1 that is at zero degrees Celsius when the ice starts melting.
Continue the process of heating and stirring the ice cubes till the ice completely melts
and converts to water. Again note the temperature, t2 when the ice
has melted completely. We can observe that the temperature remains
at zero degrees Celsius. Now take the mean of these two temperatures
t1 and t2 to find the melting point of ice. Since both the temperatures are at zero degrees
Celsius, we get the melting point of ice as zero degrees Celsius.(correction)
Precautions
Ice cubes should be stirred continuously to maintain a uniform temperature throughout
the experiment. The bulb of the thermometer should be kept
surrounded with ice cubes.