Boiling Salt
Edilma Howard
Adding salt to water does two things, it increases the boiling point and decreases the specific heat capacity. Specific heat capacity refers to the amount of heat that is required to raise the temperature of a substance by one degree Celsius. A liquids boiling point is the temperature at which the substance will starts to change state from a liquid to a gas.
Salt water requires a higher temperature before transitioning from a liquid to a gas than fresh water does due to the phenomenon known as boiling point elevation. The addition of any non-volatile solute (such as salt, baking soda or sugar) to a liquid will cause a decrease in that liquids vapor pressure. A liquid will start to boil when its vapor pressure is equal to the atmospheric pressure, so a lower vapor pressure means you need a higher temperature to boil the water.
This phenomenon also explains why water boils at a lower temperature at the top of a mountain than it does at sea level. On the top of a mountain there is less atmospheric pressure so it will take less time for the vapor pressure to match that value. When salt is added to a pot of water is also makes it more difficult for water molecules to escape from the pot and enter the gas phase as vapor or steam. This is another contributor to the higher boiling point of salt water compared to that of fresh water.
The lower heat capacity of salt water is triggered by the bonding of salt ions to water molecules. These salt ions hold the water molecules in place, making it more difficult for them to move freely. As a result, the non-salt bonded molecules receive more of the energy provided by the heat transfer occurring through the stove and will get hotter and boil faster.
Pot A (just water) will have a higher heat capacity and will require more energy to boil. The salt in pot B would have dissolved and now has a lower heat capacity than pot A. The pot containing a 20% salt concentration will heat up over 25 times faster and win the race to reach its boiling point, however, this would cause the water to be extremely salty and make the food inedible.
The boiling point of salt water is higher than that of pure water. It depends on the concentration of salt; however, for typical cooking concentrations, the increase is very slight. For example, a 10% salt solution boils at about 102C, which is 2C higher than the boiling point of pure water.
When salt is added to boiling water, it increases the boiling point of the water, a phenomenon known as boiling point elevation. This means the water needs to reach a higher temperature before it starts to boil.
Salt actually increases the boiling point of water, not lowers it. This increase is due to the presence of dissolved ions from the salt, which interfere with the formation of vapor bubbles necessary for boiling, effectively requiring a higher temperature to overcome these interactions and start the boiling process.
I want to use some 3-5 cm thick slices of a log for a project and had the chance to get some freshly cut ones. Found on the internet, that cooking in salt water drains all the stuff (proteins?) from inside the wood, so that only salt water remains, which should then dry more quickly.
It might be comparable to driftwood, which has been in water for a long time and therefore completely cleansed.
Make the wood dry faster. Here is the caveat: the wood must be wet enough to be easily carved/hollowed out, but it must not dry too quickly or it will crack. This is usually done by storing the burl in wet towels or in the freezer in-between work sessions.
In school we used to re-boil our cup workpieces before working on them again, because it would take more than the one hour of wood shop class a week to finish carving the cup. After boiling, the wood carved like hot butter.
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The only survivor is slice D, it has no cracks at all. The others are now Pac Man. So I got a tiny success here.
I leave this detailed data open for scientific interpretation
If you're adding 1 teaspoon (less than 3 grams) of salt to a liter (34 fluid ounces) of water, "it doesn't really make so much of a difference," said Lesley-Ann Giddings, an assistant professor of chemistry and biochemistry at Middlebury College in Vermont.
In order for water to boil, its vapor pressure has to equal the pressure of the atmosphere, Giddings said. That's partly why water boils at a lower temperature on top of Mount Everest than it does at sea level. There's less atmosphere, or lower pressure, pushing down on the water on the mountain, at 29,000 feet (8,800 meters), she said.
However, let's envision a pot of water on a burning stove at sea level. When salt is added, it makes it harder for the water molecules to escape from the pot and enter the gas phase, which happens when water boils, Giddings said. This gives salt water a higher boiling point, she said.
"The temperature of saltwater will get hotter faster than that of pure water," Giddings said. "But it still has a higher boiling point, and the mass is still greater when you add salt to the same volume of water, so this doesn't mean that the saltwater boils faster."
The 100 g of water in Pot A has a high heat capacity, meaning that it requires a substantial amount of energy to bring this water to a boil. In contrast, the salt in Pot B has now dissolved, and dissolved salt has a lower heat capacity than pure water does, according to an article by Mike Dammann, the manager of the Inorganics Section at The Southwest Research Institute in San Antonio, Texas.
Moreover, pot B has only 80 g of water, meaning it has less water to heat up than pot A does. "Twenty percent saltwater will heat up almost 25 percent faster than pure water and will win the speed race to the boiling point," Dammann wrote in an explanation online.
Editor's Note: This story was updated at 9:56 a.m. EDT on June 1, 2021 to correct a conversion. In the hypothetical scenario with two pots, 100 grams of water is 3.5 ounces, not 2.5 ounces as previously stated.
Laura is the archaeology and Life's Little Mysteries editor at Live Science. She also reports on general science, including paleontology. Her work has appeared in The New York Times, Scholastic, Popular Science and Spectrum, a site on autism research. She has won multiple awards from the Society of Professional Journalists and the Washington Newspaper Publishers Association for her reporting at a weekly newspaper near Seattle. Laura holds a bachelor's degree in English literature and psychology from Washington University in St. Louis and a master's degree in science writing from NYU."}), " -0-10/js/authorBio.js"); } else console.error('%c FTE ','background: #9306F9; color: #ffffff','no lazy slice hydration function available'); Laura GeggelSocial Links NavigationEditorLaura is the archaeology and Life's Little Mysteries editor at Live Science. She also reports on general science, including paleontology. Her work has appeared in The New York Times, Scholastic, Popular Science and Spectrum, a site on autism research. She has won multiple awards from the Society of Professional Journalists and the Washington Newspaper Publishers Association for her reporting at a weekly newspaper near Seattle. Laura holds a bachelor's degree in English literature and psychology from Washington University in St. Louis and a master's degree in science writing from NYU.
Yup, plain boiling water is a natural weed killer. It has the added benefit of being free (besides the cost of electricity to boil the water) and salt-free, because adding salt to your yard changes the chemical balance of your soil.
Be careful. Boiling water is dangerous. Instead of carrying a pot of boiling water to your backyard, I suggest transferring the hot water to a metal watering can which is much easier and safer to carry.
I'd say look at the values in the back of the envelop about the amount of sodium. If it's relatively high (I'd say about 2g per 100 grams), then I wouldn't put any more salt. If it's lower then it's probably a safe bet to add some salt.
As usual though, it's mostly a matter of personal taste, a little bit of salt in the water will not make them overly sticky or mushy, especially because they have to cook for a short time (typically 2-3 minutes).
Salt is an important part of the chemistry of taste, and nearly all food requires at least some additional salt at various stages of cooking. (Notable exceptions are pre-packaged, heat-and-serve-style, or packet/box mix convenience foods, which are often already high in sodium.)
In the case of pasta, even when there is salt used in manufacturing, you still want to salt your pasta water. Adding "a big pinch" (a tablespoon) to several liters of pasta water results in a relatively small amount of added salt absorbed into the pasta, with much of it staying in the water itself. However, that bit that gets absorbed does go into the pasta and is more effective at making the pasta(or gnocchi) taste like pasta than relying solely on salt from cheese, sauce, or other surface treatment. With dried pasta specifically, the way it rehydrates while cooking makes using salted water even more important.
These students were overjoyed for the task because their teacher had informed them that it would count towards their Continuous Assessment (CA) test score for the current term. Before cooking, the students were to write down the methods and ingredient lists and conduct a market survey, as was customary.
Despite the fact that both lists had identical ingredients, we discovered that one differed from the other by one step. One student stated that we add salt to the water and bring it to a boil, whereas the other stated that we let the water boil before adding salt. This piqued our interest, so we decided to put it to the test to know which of the two would boil faster: saltwater or freshwater?
A boil is a situation when the heat affects the liquid content in a vessel and produces bubbles of gas that rise to the surface of the liquid, agitating it as they rise. This can be experienced as a result of boiling points.
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