Steam is formed at 100°C but I see “steam” being produced at less than that temperature. What is that and why isn’t it steam?
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It first must take in energy to transform from a liquid into a gas, knwon as the heat of enthalpy. This is also true for water turning into ice and ice into water, it doesn’t happen instantly at 0c.
It first must take in energy to transform from a liquid into a gas, knwon as the heat of enthalpy. This is also true for water turning into ice and ice into water, it doesn’t happen instantly at 0c.
You can’t see steam (which is transparent water gas). You are seeing water vapor (larger visible droplets).
You can’t see steam (which is transparent water gas). You are seeing water vapor (larger visible droplets).
That steam you see could be condensed water on particles in the air, but it’s also important to note that there will still be some water vapor in the air at 80-90 C. Temperature is a measurement of the average kinetic energy of molecules in a system. At any temperature there will be some energetic/fast molecules and there will be some nonenergetic/slow molecules. The higher the temperature, the more fast molecules there are and the faster they are. At any temperature there will be some exceptionally fast molecules that is able to vaporize. As the temperature gets higher more of the molecules will be fast enough to vaporize. The boiling temperature is the temperature where the pressure created by the vaporized molecules is equal to the outside pressure. At 100C almost all the molecules in water are vaporizing, but at 80C fewer but still some molecules are able to vaporize. So the steam you are seeing is also still just water!
That steam you see could be condensed water on particles in the air, but it’s also important to note that there will still be some water vapor in the air at 80-90 C. Temperature is a measurement of the average kinetic energy of molecules in a system. At any temperature there will be some energetic/fast molecules and there will be some nonenergetic/slow molecules. The higher the temperature, the more fast molecules there are and the faster they are. At any temperature there will be some exceptionally fast molecules that is able to vaporize. As the temperature gets higher more of the molecules will be fast enough to vaporize. The boiling temperature is the temperature where the pressure created by the vaporized molecules is equal to the outside pressure. At 100C almost all the molecules in water are vaporizing, but at 80C fewer but still some molecules are able to vaporize. So the steam you are seeing is also still just water!
If you have water at 80C, then that is the *average* temperature of all the water molecules. Specifically, temperature indicates the average energy. Some molecules are moving faster and escape as steam. As high energy molecules leave, the lower energy molecules are left and the temperature drops, if no other energy is being added, like from a stovetop.
If you have water at 80C, then that is the *average* temperature of all the water molecules. Specifically, temperature indicates the average energy. Some molecules are moving faster and escape as steam. As high energy molecules leave, the lower energy molecules are left and the temperature drops, if no other energy is being added, like from a stovetop.
There’s some good answers here already, but they’re a bit past ELI5 explanations, so I’ll try and keep this to that level. Steam is created when water molecules have enough energy to escape their liquid form. Some molecules have more energy than others and can escape well before the entire liquid mass is “boiling”. Lot’s of things can effect this, such as adding salt to water or lowering air pressure as it’s air pressure that keeps the molecules trapped in the liquid.
This can be shown using a syringe. Suck some warm, but not boiling, water into a syringe, cover the end and pull the plunger outward. The water will start boiling as there is less pressure keeping those molecules in the water, thus making it easier for them to escape. So you can actually make water boil without ever being near 100°C.
What’s really interesting is that when water boils, it actually cools down. The temperature of water is the amount of energy (heat) within the water. As these energetic molecules escape, they take that energy with them, leaving the liquid water cooler. It’s why a boiling pot doesn’t instantly evaporate.
So liquid water doesn’t need to be 100°C to create steam, only individual molecules need enough energy to escape the liquid mass to create steam. We only say 100°C is boiling point, because that is when you will see liquid water “boil” at sea level.
There’s some good answers here already, but they’re a bit past ELI5 explanations, so I’ll try and keep this to that level. Steam is created when water molecules have enough energy to escape their liquid form. Some molecules have more energy than others and can escape well before the entire liquid mass is “boiling”. Lot’s of things can effect this, such as adding salt to water or lowering air pressure as it’s air pressure that keeps the molecules trapped in the liquid.
This can be shown using a syringe. Suck some warm, but not boiling, water into a syringe, cover the end and pull the plunger outward. The water will start boiling as there is less pressure keeping those molecules in the water, thus making it easier for them to escape. So you can actually make water boil without ever being near 100°C.
What’s really interesting is that when water boils, it actually cools down. The temperature of water is the amount of energy (heat) within the water. As these energetic molecules escape, they take that energy with them, leaving the liquid water cooler. It’s why a boiling pot doesn’t instantly evaporate.
So liquid water doesn’t need to be 100°C to create steam, only individual molecules need enough energy to escape the liquid mass to create steam. We only say 100°C is boiling point, because that is when you will see liquid water “boil” at sea level.
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