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EXPERIMENTS IN IP-COACH SYSTEM:
Thermal Properties of Matter
Melting Point of Sodium Thiosulfate
 Physical Principle:
When a solid is transformed into a liquid by the addition of thermal energy,
the process is known as melting. When a solid is warmed to its melting point,
the slow continuing addition af heat results in the materialīs gradual and
complete liquefaction at the fixed temperature.
Aim:
1. The purpose of the experiment is to show that the melting point as well as
the freezing point of sodium thiosulfate keeps constant.
2. The melting point and the freezing point of a crystalline solid - sodium
thiosulfate are the same. (t=48,2˚C)
Materials:
beaker, sodium thiosulfate (Na2S2O3.5H2O), water bath with heater, temperature
sensor, computer with interface system IP COACH , stand, adjustable clamp
Preparation:
Connect the temperature sensor to the selected chanel of the interface system
that is already calibrated for temperature measuring. Set the measuring time
into 10 min. Put small pieces of sodium thiosulfate into the beaker and insert
a temperature sensor into it. Fasten the beaker into the clamp of the stand and
immerse it into the water bath (fig.1).
Realization:
Start the measuring procedure (temperature measuring) and switch on the heater
of the water bath. Sodium thiosulfate should be stirred all the time with a
help of temperature sensor. After melting of all amount of it measure its
temperature for further 3 minutes. Then finish the measuring procedure and save
the results. Start the measuring again and now measure the process of freezing.
Processing:
From the diagram state the melting point of sodium thiosulfate.
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