Scenario: You spray a solution of 70% Ethanol and 30% water on a piece of paper – do all of the ethanol molecules evaporate or do some of the ethanol molecules get trapped inside the paper fibers and never evaporate? Evaluate for a year in a room with a pressure of 1 atm and a temperature of 25 Degrees Celsius.

Answer: If you’ve ever spilled some liquid onto a piece of paper and watched it slowly disappear you might wonder if there are any traces left on the paper. When it comes to a solution of 70% ethanol and 30% water, things get interesting.

Ethanol and Its Properties Ethanol, commonly known as alcohol, is a volatile substance, meaning it easily evaporates. It’s that same quality that gives it its characteristic smell. But, what makes ethanol so keen to take to the air?

Understanding the 70% Ethanol and 30% Water Mixture You might wonder, why not 100% ethanol? Well, a 70:30 mix isn’t just a random pick. This ratio often provides optimal disinfecting properties. Moreover, the presence of water can enhance the effectiveness of ethanol, especially in microbial killing. Who would’ve thought?

Paper and Its Composition Paper isn’t just a plain sheet. It’s a complex weave of fibers, spaces, and microscopic structures. When you spill something on it, the liquid doesn’t just sit; it gets absorbed into these tiny pockets, thanks to capillary action.

Evaporation Explained Evaporation is like nature’s magic trick. It’s the process where molecules escape from a liquid into the atmosphere. It’s why puddles dry up and why your clothes don’t stay wet forever. But, how does this play out with our ethanol-water mixture?

How Ethanol Interacts with Paper When you spray our star mixture onto paper, the ethanol gets eagerly absorbed. But due to its volatile nature, it’s also itching to evaporate. However, can all of it make its grand escape?

External Factors Affecting Evaporation Just like how we need the right mood for a good dance, ethanol needs the right conditions to evaporate. Temperature, air pressure, the moisture in the air – all play their part. Ever noticed how things dry slower on a humid day? That’s Mr. Humidity being a party pooper for evaporation.

Long-Term Impact on Paper After a long dance, even the best dancers need to rest. Similarly, after a significant amount of evaporation, the paper might retain trace amounts of ethanol, trapped in its tiny nooks and crannies. And yes, while the paper seems dry, on a molecular level, there might still be some guests who’ve overstayed their welcome.

Practical Implications So, the next time you’re spraying some disinfectant on a piece of paper or cleaning a stain, remember our little exploration into the world of evaporation. Knowing what happens on a microscopic level can be quite empowering and oddly satisfying!

Conclusion In our day-to-day life, we often overlook the little wonders of science happening right under our noses. While the majority of ethanol from a 70% ethanol and 30% water solution will evaporate from paper, especially in standard room conditions, it’s fascinating to think that there might still be tiny amounts playing hide and seek within the paper fibers.


  1. Why use a 70% ethanol and 30% water mixture?
    • It’s often used for its optimal disinfecting properties.
  2. Does paper absorb all liquids the same way?
    • No, the absorption can vary based on the liquid’s properties and the paper’s composition.
  3. Can 100% ethanol evaporate completely from paper?
    • While most of it will, trace amounts might remain trapped within the paper’s structure.
  4. How does humidity affect evaporation?
    • Higher humidity can slow down the evaporation process as the air is already saturated with moisture.
  5. Are there any other factors affecting evaporation?
    • Yes, factors like air circulation, the presence of other substances, and the nature of the surface play a role.