tempest in tea cup
The objective: The objective of this study is to explore microwave
heating and to examine the factors that impact post-super heating
nucleation, in which a sudden violent boiling event occurs when a
liquid is heated past its boiling point. Specifically, is post-super heating
nucleation affected by:
(1) the shape of the container?
(2) the presence of pores on its internal surface?
(3) the presence of scratches on an otherwise glossy internal surface? and
(4) dissolving solutes such as salt, sugar and coffee in the water? These
questions formed the basis of this experiment's hypotheses
Methods/Materials
Materials: Microwave oven; Tap water; Distilled water; Glass
containers in 3 shapes - walls flaring upwards, straight walls,
and walls flaring downwards; Non-glossy internal surface container
with small pores (Styrofoam); Salt, sugar, and coffee; Insulated gloves.
Protocol to measure time to post-super heating nucleation: Put 200 ml.
of liquid into container and place in microwave oven. Heat for 7 minutes.
Observe when boiling first occurs and record time elapsed from initiation
of heating. Let heating continue until sudden nucleation and accompanying '
explosion' occurs and again record the elapsed time. Use insulated gloves to
carefully remove container. Repeat this protocol for each set of independent
variables described in each hypothesis - different container shapes, container
materials, container surfaces, and solutions.
Results
The container with upward flared walls had the highest time to post-super heating
nucleation followed by the one with straight walls and the one with walls
flaring downwards. The container with pores on the internal surface had no
post-super heating nucleation; once normal nucleation began, it continued.
The container with scratches on the internal surface had similar results.
Finally, the salt solution too had no post-super heating nucleation, while
the time to post-super heating nucleation for the sugar and coffee solutions
was longer than that for plain water. Error bars of one standard deviation
were used for analysis.
Conclusions/Discussion
The observations supported all 4 hypotheses. Post-super heating nucleation
is impacted by the characteristics of the container - the shape and the internal
surface - as well as the characteristics of the liquid being heated. Results from
this experiment offer suggestions for better regulating post-super heating
nucleation and avoiding its catastrophic effects.
This project examined post-super heating nucleation in microwave heating.
Specifically, I studied the effect of varying a container's characteristics,
as well as those of the liquid being heated, on the time to post-super heating nucleation.
The objective: The objective of this study is to explore microwave
heating and to examine the factors that impact post-super heating
nucleation, in which a sudden violent boiling event occurs when a
liquid is heated past its boiling point. Specifically, is post-super heating
nucleation affected by:
(1) the shape of the container?
(2) the presence of pores on its internal surface?
(3) the presence of scratches on an otherwise glossy internal surface? and
(4) dissolving solutes such as salt, sugar and coffee in the water? These
questions formed the basis of this experiment's hypotheses
Methods/Materials
Materials: Microwave oven; Tap water; Distilled water; Glass
containers in 3 shapes - walls flaring upwards, straight walls,
and walls flaring downwards; Non-glossy internal surface container
with small pores (Styrofoam); Salt, sugar, and coffee; Insulated gloves.
Protocol to measure time to post-super heating nucleation: Put 200 ml.
of liquid into container and place in microwave oven. Heat for 7 minutes.
Observe when boiling first occurs and record time elapsed from initiation
of heating. Let heating continue until sudden nucleation and accompanying '
explosion' occurs and again record the elapsed time. Use insulated gloves to
carefully remove container. Repeat this protocol for each set of independent
variables described in each hypothesis - different container shapes, container
materials, container surfaces, and solutions.
Results
The container with upward flared walls had the highest time to post-super heating
nucleation followed by the one with straight walls and the one with walls
flaring downwards. The container with pores on the internal surface had no
post-super heating nucleation; once normal nucleation began, it continued.
The container with scratches on the internal surface had similar results.
Finally, the salt solution too had no post-super heating nucleation, while
the time to post-super heating nucleation for the sugar and coffee solutions
was longer than that for plain water. Error bars of one standard deviation
were used for analysis.
Conclusions/Discussion
The observations supported all 4 hypotheses. Post-super heating nucleation
is impacted by the characteristics of the container - the shape and the internal
surface - as well as the characteristics of the liquid being heated. Results from
this experiment offer suggestions for better regulating post-super heating
nucleation and avoiding its catastrophic effects.
This project examined post-super heating nucleation in microwave heating.
Specifically, I studied the effect of varying a container's characteristics,
as well as those of the liquid being heated, on the time to post-super heating nucleation.
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