Other factors that influence evaporation rates are the surface area, temperature and airflow. Cleanup Flush any unused rubbing alcohol down the sink with plenty of cold water. Wash your hands with soap, and clean your work area. This activity brought to you in partnership with Science Buddies. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue.
See Subscription Options. Go Paperless with Digital. Key concepts Physics Evaporation Heat transfer Temperature Introduction Have you ever wondered why we sweat when our environment is hot or when we exercise? Materials Rubbing alcohol Water Two small cups or bowls Tablespoon Pipet or medical dropper Preparation Fill one small cup or bowl with one tablespoon of water.
Fill the second small cup or bowl with one tablespoon of rubbing alcohol. Procedure Suck up some water from the first bowl water using the pipet or medical dropper. Carefully drop one or two drops on the back of our hand and spread the liquid with your fingers.
When the water touches your skin, how does it feel? Blow softly over the skin area that you just covered with water.
Does your skin feel any different when blowing on the water? Can you sense a difference in temperature while blowing? How does it feel? Rinse your pipet with some rubbing alcohol and then suck up some of the alcohol with your pipet.
Drop the same quantity of liquid on the back of your other hand and spread the liquid with your fingers. Does the alcohol feel different when it touches your skin? Again, blow over the area on your hand where you put the alcohol. What sensation do you feel? Does your hand feel warmer or cooler compared with water when blowing on the liquid? Can you think of a reason why? Extra : Find out how fast rubbing alcohol and water evaporate. Put the same small amount of water and rubbing alcohol in two different cups and place them both in the sun.
There are plenty of factors at play. These factors include temperature, air pressure, humidity, surface area, and wind speed. You can learn more below on how fast alcohol evaporates. Evaporation is the process of liquids turning into gas. In a liquid, the molecules are attracted to each other enough for them to always make contact.
But they are loose enough to move around and flow. However, these molecules constantly want to be free. Think of them like birds in a big cage. But as soon as you leave the cage door open, they fly off. When those liquid molecules escape, they turn into gas or vapor form. The cage door that keeps those from escaping is the air pressure in their environment. You can do many things.
One thing is to put the liquid in an environment with a lower air pressure. That scenario is why liquids evaporate faster at higher altitudes. In those places, air pressure is lower. Another thing you can do is give those molecules more energy so they can push back. And we give them that energy through heat. That is the reason liquids evaporate faster at higher temperatures. The boiling point is the temperature at which a liquid boils. You say that a liquid is boiling when the pressure of its vapor form is the same as the pressure of the surrounding surrounding air.
The boiling point of every liquid is different. The difference is because of their unique molecular structures. The boiling point also changes at different air pressures. At higher altitudes where the air pressure is lower, the boiling point is also lower. So in a place like Denver, which is about 1 mile 1.
All alcohols have a boiling point lower than water. So why do you need to know about boiling points? Because liquids with lower boiling points evaporate faster. Besides temperature and pressure, there are other factors that affect how fast a liquid evaporates. Evaporation occurs on the surface. The reason is that they have other liquid molecules on top of them. Hence, the larger the surface area, the faster evaporation happens. Humidity is the amount of water molecules in the air.
For water, the higher the humidity, the slower the evaporation. The reason is that the air already has lots of water vapors. Hence, it can only take in a few. Improve this question. It might help someone to give you a better answer. Otherwise, you could certainly give this a try at home with a lower purity ethanol and see if you can extrapolate.
Is the surface wettable by ethanol? Suffice to say, ethanol evaporates quite rapidly with respect to water due to its relatively low specific heat capacity and high vapor pressure.
Add a comment. Active Oldest Votes. A complete model includes consideration of the following: Constants the Boltzmann constant The ideal gas constant the free energy change of vaporization of ethanol not actually constant, but it varies only slightly over the temperature range the vapor pressure of ethanol as a function of temperature the mass of an ethanol molecule the heat capacity of the surface variables temperature of the air volume of ethanol temperature of the surface atmospheric pressure needed for mean free path corrections velocity of air currents So, in principle, you could do it.
Improve this answer. Ben Norris Ben Norris 41k 8 8 gold badges silver badges bronze badges. Plugging in 5 variables looks so much easier than doing dozens of complicated experiments. Resin 3D printing costs hours per print plus money. Are there books on this topic? Community Bot 1. Jan Jan Featured on Meta. Now live: A fully responsive profile. Related 4. Hot Network Questions. Question feed.
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