Have you ever heard that salt makes water boil faster? If so is this true? My son says salt raises the boiling temperature and it isn't true.
A small amount doesn't make a LOT of difference but it does make it boil differently. Maybe just a bit of difference.
http://www.ehow.com/how-does_###-###-####_table-make-wate...
Your son is right. Salt actually makes it take LONGER for water to come to a boil, because it has to reach a higher temp, and will boil at a hotter temperature than freshwater can reach.
HOWEVER
Pure water doesn't boil.
The bubbling/roiling boil is cause by impurities in the water itself giving a surface for the gas bubbles to "stick" to long enough to form a bubble. If you have VERY pure water and a VERY clean pot/glassware container the water will get extremely hot but not actually boil. I do this as a science experiment with 'my' kids when I'm teaching chem. Because the moment you put ANY object in (salt, a rock, a spoon, whatever) the water comes EXPLODING out of the container. ROFL... I actually did it to myself on accident a few weeks ago. Zapped some water for chicken stock, but hadn't added the bouilon cube. Whoops. Because I dropped the cube in and POOF. Scalding hot water everywhere and 4 cups of super heated water reduced down to 1/2 cup in less that 5 seconds of frantic off gassing.
I'm only laughing because I realized what I did the moment my fingers left the cube, and I LEAPED back slamming the door shut as I did so, so no one got burned.
Part of the reason I do this as an experiment with "my" kids, is because it's good kitchen safety. Because of the impurities of city water (it's gross stuff, city water) you usually don't find as many burn cases as one used to... but it's still good kitchen-safety to always, always, always have something "in" a pot or glass of water when you heat it up.
The other experiment we do with boiling water and salt (cooking) has to do with pasta. AKA fresh water, salt water, fresh water come to a boil and then salt added. We time and temp to reach boiling, and then we time and temp pasta. ((It's not that the salt flavors the pasta as you're cooking it, it's that the higher temp cooks the pasta differently than fresh water)).
Fun stuff!
Your son could've been in my chemistry class! I always tell my students to go home and "teach their parents" when we talk about this. Since salt water requires a higher temperature to boil, the food will cook faster in boiling salt water, but it doesn't cause the water to boil faster (actually slower since it will require heating to a higher temperature). But, you would have to add quite a bit of salt for it to really cause any noticable effect. Yea for your son! He's learning chemistry!
As I understand it (and if I recall correctly from my chemistry classes MANY years ago) adding salt to water doesn't make it boil faster, but it does increase the boiling point of the water. So, whatever you are cooking in that boiling salt water will cook faster since your water is boiling at a higher temperature. I also think you would have to add quite a bit of salt to make a difference either way. The little we add when we cook probably wouldn't make much of a difference either way.
It has been 14 years since I studied this. You may want to do your own research. LOL!
Your son is right. He deserves ice cream :)
to the best of my knowledge from my school days....
salt makes water "heavier" or denser and therefore takes LONGER to boil.
I just know the saying "a watched pot never boils".
Obviously, water will boil eventually regardless of what you do to it if it's hot enough.
Salt LOWERs the freezing and raises boiling temp of water. (http://www.sciencebase.com/science-blog/how-does-salt-aff...)
I don't think this is true. I know that most people add salt to water before it boils (if you're cooking pasta or potatoes or eggs) to flavor the food while it's cooking, at least that's what I do! I'd google it...I've found the answers to lots of the earth's greatest questions that way! ;)
