Why boiling when cold bottle is placed in hot bath?
Why boiling when cold bottle is placed in hot bath?
(OP)
Ok, I know that this forum is supposed to be for industrial-type questions, but the physics behind this is boggling me.
When I heat my baby's bottle, I first bring a bowl of water to a rolling boil in the microwave. I let the bubbling subside and then place a cold (40 deg F) bottle of milk in the water.
I immediately get a second or two of violent boiling when I put the cold bottle in the hot water. I am confused by this. I could certainly understand it if the temperatures were the other way around. But why do I get boiling when I place a 40 deg F bottle into a 212 deg F bath. The bowl is open to atmosphere so I don't see how there could be any "flash" steam. Any thoughts?
When I heat my baby's bottle, I first bring a bowl of water to a rolling boil in the microwave. I let the bubbling subside and then place a cold (40 deg F) bottle of milk in the water.
I immediately get a second or two of violent boiling when I put the cold bottle in the hot water. I am confused by this. I could certainly understand it if the temperatures were the other way around. But why do I get boiling when I place a 40 deg F bottle into a 212 deg F bath. The bowl is open to atmosphere so I don't see how there could be any "flash" steam. Any thoughts?





RE: Why boiling when cold bottle is placed in hot bath?
RE: Why boiling when cold bottle is placed in hot bath?
My thinking: after removing the heat, it appears the water is in a state of superheat. When introducing a spoon or any other (even cold) object, steam bubbles can form because of the created turbulence, or because the addition of surface irregularities that may serve as nucleation sites for bubbles to form.
If my thinking is correct this would frequently happen when the water boiling in the microwave oven is done by using smooth wall containers.
RE: Why boiling when cold bottle is placed in hot bath?
Whether your baby's bottle is cold or not is not the issue. Insert any extra surface into that superheated water and you are likely to nucleate boiling. Just be careful it is not a spoon- your fingers might be too close to the water and you might get an unwelcome suprise.
RE: Why boiling when cold bottle is placed in hot bath?
RE: Why boiling when cold bottle is placed in hot bath?
You are correct that microwaving very easily creates superheated water. However, the OP states that he gets a rolling boil, which to me indicates boiling at saturation.
RE: Why boiling when cold bottle is placed in hot bath?
Depending on the geometry of the water container and the oven type, it has been reported that radio microwaves quickly and directly heat up the exposed surface resulting in rolling boil, while the remainder is being heated up mostly by conduction and may reach a state of superheat as explained by moltenmetal.
RE: Why boiling when cold bottle is placed in hot bath?
RE: Why boiling when cold bottle is placed in hot bath?
RE: Why boiling when cold bottle is placed in hot bath?
Often when you boil water in a microwave the 'rolling boil' is mostly outgassing, not actually steam bubbles.
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RE: Why boiling when cold bottle is placed in hot bath?
rmw
PS BronYrAur, I thought it a very appropriate topic for this forum.
RE: Why boiling when cold bottle is placed in hot bath?
RE: Why boiling when cold bottle is placed in hot bath?
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Why boiling when cold bottle is placed in hot bath?
RE: Why boiling when cold bottle is placed in hot bath?
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Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Why boiling when cold bottle is placed in hot bath?
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Why boiling when cold bottle is placed in hot bath?
Another trick: heat up the water to boiling again, remove it from the oven, then immediately insert a dry wooden coffee-stirrer, or a wooden popcicle stick into the water. Foosh! The water boils violently. The dry wood contributes a layer of air to the water, and the air fills with steam and expands into a mass of hot foam.