Figure 4. This schematic shows how to connect the components
needed for this experiment, including the LM32 temperature sensor
and the optional stirring motor to the VEX microcontroller.
We will now repeat the same experiment described
above, but dissolve one tablespoon of salt (or sodium
chloride) in the warm water [H20 + NaCl]. Try to keep
the starting and ending temperatures the same. Record
temperature readings captured by the
Easy C terminal to another file, since we
will use both data files for analysis.
Finally, use the optional motor with a
plastic gear or paddle attached (which is
described next) to stir the pure water and
salt water at 20 second intervals. Again,
we use the microcontroller to monitor the
temperature of the water at these 20
second intervals until the water reaches
room temperature. Collect this data using
the Easy C debug window and save the
Safety Warning: Use only warm
water from the sink so as to avoid getting scalded.
Wear goggles for this experiment. Place a splash guard
over the measuring cup. Don’t boil the water on the
stove to heat it; just use warm water from the faucet.
Figure 5. The measuring cup, temperature
sensor, and optional VEX motor used to stir the
solution are shown here. Most of these
components are available from the VEX kit or
around the house.
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