Friday
September 19, 2014

Homework Help: science?

Posted by ~christina~ on Tuesday, August 21, 2007 at 6:07pm.

Why would a potato cook faster if you poke holes in it with a fork before microwaving it?

~My thinking is that it would increase the surface area..but this could be just partially why it cooks faster.

Thank You =D

I dont know in a microwave it cooks faster. If you poke holes in it, steam escapes, and it does not explode.

I dont know in a microwave it cooks faster. If you poke holes in it, steam escapes, and it does not explode.

Actually I've never had a potato explode on me LOL
I've originally cooked it without poking holes in it but it took longer. A cooking show had a host which said to poke holes in a potato but they didn't say why. After I tried that I found it cooked faster than if I hadn't poked holes in it. I just wondered why it did cook faster.

Thanks Bob Pursley =)

I just thought of this...why would something explode in the microwave during heating in the first place?
(I've never had a potato do that but I've done that with an egg)

(this is even more interesting than why a potato cooks faster after holes are poked in it)



I've occasionally had a baked potato blow up in a regular oven. I try to remember to prick them with a fork before I bake them now. I don't know why they blew up -- but obviously the heated potato created pressure and caused it to expand beyond its skin.

If you heat something up in a pan with water on a fire, then the temperature will rise gently to boiling point. As you near the boiling point of ater the temperature will rise more slowly, because water will evaporate faster and faster.

In a microwave, the temperature you'll reach will be much higher than the boiling temperature of water, so the pressure inside the egg can also become much higher causing the egg to break. Note that the egg shell acts as a pressure cooker as long as it is intanct.

You can also let water boil explosively in a microwave. If you put a cup of distilled water in a microwave and heat it, then the temperature can exceed the boiling temperature of water without the water boiling.

The heating process in the microwave is very gentle. There are no large temperature gradients, (compare with heating in a kettle where the bottom of the ketle is hot). The free energy for water ablove its boiling point is lowest in the "steam phase", but it has still a higher local minum at a "water phase", which is called superheated water.

The superheated water needs to be perturbed a bit to be able to move from its local minimum it is trapped in to the global minimum. Taking the water out of the microwave will be enough to cause this transition. Because the water is hotter than 100 C it will boil explosively.

I have never tried this, because it is a dangerous experiment...

Ms.Sue, that's a funny story I must admit, but I don't bake potatoes just microwave them. I find that when I buy baked potatoes they are drier than if you just microwave them. =D

Count Iblis:

That is Very interesting. I've read in the newspaper that a girl got burned after the water was heated in the microwave and after she took it out it exploded in her face. I assumed it boiled explosively and that's why it looked like it exploded I guess. I was actually going to mention that with the above post but I decided not to. But since you mention it, I've heard that to prevent this you can go and put for example a wooden chopstick in the cup of water when you boil it, but why that would work is beyond me.. Do you know why that would work?



Yes, almost anything placed in the cup will prevent superheating. In the chemistry lab it is common practice to place "boiling stones", glass beads, or shards of some material, in water being heated so that when it boils it will do so without "bumping". The bumping is caused by the water superheating, then explosively boiling to relieve the excess heat/pressure. Of course, the material placed in the water to prevent bumping must be extremely pure if we are to use the water later for analytical purposes. In my younger days, I found that almost nothing was pure enough for me to use (I was analyzing material in the 1 ng region) and I found that swirling the beaker, for example, with insulated beaker tongs, (but still touching the hot plate), prevented the bumping and I had no contamination from outside sources. I didn't know 60 years ago that such information might come in handy someday. ;-).

XD
interesting Dr.Bob...

I guess if it is in the ng region then any form of contamination no matter how minimal would affect results.
I would have to say that swirling the beaker with tongs has to be a delicate task since it would be very easy to go and swirl some of the boiling solution out of the beaker.

How has it come in handy Dr.Bob? (do you mean they do this these days when doing experiments[swirling]?)

It's easy to get contamination when determining quantities in the region of 1 ng or less.
Spilling is no problem since the size of the beaker is determined by the volume of water being boiled (and swirled).
It has come in handy in answering this question asked by Count Iblis.
By the way, boiling chips and glass beads are easy to purchase from chemical houses now but they were not available commercially back in the good old days. We (us lab jocks) sacrificed the cheapest dinner plate we had and the pieces lasted forever as boiling chips.

XD cheap dinner plates...the residue of food would be a contaminant lol.

~was there a question asked by Count Iblis?? (this is rhetorical of course but I seriously think I was asking the questions Dr.Bob..not Count Iblis)

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

Biology - Equal sized potatoes are dipped into water,weak sucrose and strong ...
Ap Biology - We performed a lab that studied osmosis in potato cells. We put ...
English - 1. Would you say hi to your mother? 2. Would you say hello to your ...
Chem - KHC4H4O6(s)<-> K+ (aq)+ HC4H4O6-(aq) 1) If the above reversible ...
Biology - what would b possible sources of errors for a potato experiment ...
algebra - Find the volume of a right circular cylinder whose base has an area of...
Science - Luther Burbank was a plant breeder who developed a strain of potato ...
Science - Luther Burbank was a plant breeder who developed a strain of potato ...
PHYSICS - You shoot your potato gun horizontally from shoulder height, which is...
science - 1. For the three cubes shown below, determine their surface area, ...

Search
Members