You’ve likely heard that “a watched pot never boils.” If you’re really hungry for some delicious pasta, rice, lentils, or potatoes it may seem like it is taking forever for the water to reach boiling point. So how can you speed it up? Does salt make water boil faster?
Adding salt to water makes it boil faster. But only to a minimal, barely discernable degree. There are two, conflicting processes at play. Here’s the science behind this myth. And 5 proven methods to get your water boiling faster.
Does water always boil at 212 °F (100 °C)? The answer is no. More on that below.
Does Salt Make Water Boil Faster?
Two things happen when you add salt to a pot of water.
1. Salt Raises the Boiling Point of Water
The first is that it raises the boiling point.
At sea level, the boiling point of water is 212 °F (100 °C). If you add 5 teaspoons of salt to 1.3 gallons (5 liters of water), it will boil at 100.04 °C (not a significant difference).
The more salt you add, the higher the boiling point.
A higher boiling point usually means that it takes longer to get to the boiling point, but once it is there, any food placed into the water will cook quicker.
2. Saltwaster Heats Faster
But here is where the second thing comes into play. Adding salt to water lowers the specific heat required to bring it to a boiling point.
This means that less energy is needed to heat up saltwater. Put simply, saltwater heats up faster, but has to get to a higher temperature in order to boil (which takes longer).
The two changes more or less cancel each other out (when a small amount of salt is used).
With the amount of salt that you would add to cooking water, you may only notice microseconds of a difference in your cooking time.
Adding a significant amount of salt does speed up the boiling process more, but with the amount of salt that would require, your food would be inedible.
Why Does Salt Increase Water’s Boiling Point?
Water molecules stick to other water molecules by means of hydrogen bonds. When salt is added to the water it separates into sodium (Na) and chlorine (Cl) ions.
Put simply, the water is more attracted to these ions than it is to other water molecules.
The negatively charged chlorine ions aline with the hydrogen side of H2O, and the positively charged sodium bonds with the oxygen side.
This adds an extra reluctance for the water vapor to exit the pot and enter the atmosphere.
Boiling Point of Salt Water
The boiling point of saltwater is variable. Elevation and salt content influence the boiling point. The more salt that’s added, the higher the boiling point.
As to how much salt is needed, here’s what Anne Marie Helmenstine, Ph.D. has to say: “The temperature needed to boil will increase about 0.5 °C for every 58 grams of dissolved salt per kilogram of water.”
That’s a 0.9° F increase, for 2 ounces of salt, in 2.2 pounds of water.
Salt does not lower the boiling point. It always increases the boiling point of water.
Why does hot water bubble more when I add salt?
Have you ever added salt to water that is nearly at a boil and suddenly the pot fills with bubbles? You may think that this proves that salt makes water boil faster.
But what is actually happening? Let’s go back to the science.
When water boils, the individual molecules (composed of 2 hydrogen atoms and 1 oxygen atom) get excited and move around very quickly.
The bubbles that form are not composed of air, rather, they are pockets of water vapor waiting to make their escape. These bubbles tend to form more quickly at nucleation sites, where there are small disturbances in the water.
You may notice these vapor bubbles forming from a scratch on the inside of your pot, or when you have a wooden spoon in the water.
Adding salt adds hundreds (if not thousands) of nucleation sites, which makes it easy for lots of bubbles to form.
But just as using a scratched-up pot isn’t making the water boil any faster, neither is the addition of salt.
So should I add salt to my water?
Even though it doesn’t really affect the cooking time, adding salt to water is a great way to flavor food.
Just make sure to add it after the water is already hot. This prevents it from scratching up your pot, as it will dissolve as soon as it hits the water.
If you are boiling water to make it safe to drink, skip the salt and try using a portable water filter.
5 Proven Methods to Boil Water Faster
So using saltwater doesn’t really work if you are trying to make water boil faster.
Here are 5 methods that actually do make water boil faster.
1. Use a shallow pan with a larger surface area
The thinner the layer of water, the faster it will boil. This is because a larger percentage of the water in the pan is being exposed directly to the heat.
This method works great if you are steaming vegetables. But don’t use too thin of a layer, because you still want some left as the water evaporates.
2. Use a smaller pot
The lesser the volume of water, the less time it takes to heat it up. So if you are cooking something small, use a small saucepan.
Use a bigger pot only when you need to. Similarly, add just enough water to cover the top of whatever food you are boiling (unless the instructions indicate otherwise).
3. Start with hotter water
This is a great trick for cooking in a hurry. Turn your electric kettle on as you begin your food preparation. Within a few minutes, you will have boiling water.
But just in case I need to say this, do not cook in your kettle, transfer the boiling water into a cooking pot, and then add your food.
Does cold water boil faster?
There is a myth that cold water boils faster than warm water. But it is not true.
4. Keep the pot covered
Keeping the lid on will trap the heat and the steam.
To take it to the next level, use a pressure cooker. A pressure cooker creates a sealed environment, preventing any heat or steam from escaping.
Because the vapor can’t escape into the atmosphere, the boiling point is also increased, causing water to boil at 250 °F (121 °C). The higher temperature makes food cook quicker.
5. Cook at a higher altitude
While it is not really feasible to cook your food on top of Mount Everest, the science is interesting.
Part of how boiling works, is that the water molecules have to have enough energy to escape into the atmosphere.
The higher the altitude, the lower the atmospheric pressure, the lower the boiling point.
For example, at the top of Mount Everest, water boils at 154 °F (68 °C).
According to the USDA Food Safety and Inspection Service, for “every 500 ft (152.4 m) increase in elevation, water’s boiling point is lowered by approximately 0.5 °C. At 8,000 ft (2,438.4) in elevation, water boils at just 92 °C (198 °F)”.
The city of Cuenca, Ecuador is located at 8,500 feet (2590 m).
The lower temperature means that water would come to a boil quicker in those locations.
While that may sound great, food doesn’t always cook properly at those temperatures. So your pasta and rice would still be crunchy, and your vegetables would still be hard.
To solve that problem, a lot of people that live in higher altitudes use pressure cookers.
What is happening scientifically when water boils?
To understand why some methods work and others do not, we first need to discuss some basics as to what is happening on a molecular level when water is boiling.
Water has three phases: solid (ice), liquid, and gas (water vapor).
At room temperature, water will slowly evaporate, leaving its liquid form and entering the air as water vapor. This is why the floor dries after you mop it, or why clothes dry on a clothesline.
According to Wikipedia, “Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere.”
When you add enough heat to a liquid, it reaches its boiling point, and evaporation becomes vaporization. The pressure in the surrounding atmosphere makes a difference.
It’s worth taking the time to boil your water correctly. Correctly boiling water can reduce your chances of getting parasites and amoebas.
What methods do you use to make water boil faster? What’s the highest (lowest) boiling point that you’ve seen in your travels?
Let me know in the comments below.
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