This question looks at the relationship between the molecular structure, polarity and
solubility of ethanol (wikipedia ethanol), water and petrol
(Wikipedia Petroleum).
This posting was made on a discussion board:
"Ethanol mixs in fuel are not a bad thing if pure. What they don't tell you its not possible to be
pure unless you buy it in sealed drums direct.
Fact ethanol absorbs water from the air and with contact.
Fact ALL fuel stations have water in the bottom of the tanks. The pickup for fuel in these tanks are
not at the bottom, so unless the water isn?t monitored and comes up too high it not a problem.
Straight petrol floats on water and doesn?t mix or absorb water.
On the other hand any ethanol mix will come into direct contact with water at all fuel stations, a fact.
So straight away your running a small % of absorbed water through your cars which will effect
some parts such a fuel injectors over time."
Green - assume this is the case
Yellow - Analyse and evaluate these comments (explain the chemistry). Do you think the
author is correct?
Pink - rephrase this so it retains the author’s intent but makes sense from a chemical
perspective.
This is Yellow - Fact ethanol absorbs water from the air and with contact. and
So straight away your running a small % of absorbed water through your cars which will effect
some parts such a fuel injectors over time."
This is Green - Fact ALL fuel stations have water in the bottom of the tanks. The pickup for fuel in these tanks are
not at the bottom, so unless the water isn?t monitored and comes up too high it not a problem.
This is in pink - On the other hand any ethanol mix will come into direct contact with water at all fuel stations, a fact.
It is true that absolute(pure) ethanol (100%) will absorb approximately 4% water from the air to make a 96% ethanol/4% water azeotrope. It won't absorb more than that from the air although one may add more water physically.
Other than that you don't have a question here.
To evaluate the author's comments about the relationship between the molecular structure, polarity, and solubility of ethanol, water, and petrol, let's break it down and analyze it from a chemical perspective.
1. "Fact ethanol absorbs water from the air and with contact."
This statement is true. Ethanol is hygroscopic, which means it can absorb water from the atmosphere, as well as through direct contact.
2. "Fact ALL fuel stations have water in the bottom of the tanks. The pickup for fuel in these tanks are not at the bottom, so unless the water isn't monitored and comes up too high, it's not a problem."
This statement assumes that all fuel stations have water in the bottom of their tanks. While some fuel stations may have water accumulation, it is not true for all stations. Additionally, the pickup for fuel usually occurs above the bottom of the tank, so unless there is excessive water buildup that reaches the pickup, it should not cause significant issues.
3. "Straight petrol floats on water and doesn't mix or absorb water."
This statement is generally true. Petrol (also known as gasoline) is nonpolar, and since water is polar, they do not mix well and tend to separate. Petrol does not readily absorb water.
4. "On the other hand, any ethanol mix will come into direct contact with water at all fuel stations, a fact."
This statement is partially true. Ethanol-containing fuels, especially those with a higher ethanol concentration, can come into contact with water if there is water accumulation in the fuel tanks. However, it is not accurate to say that all fuel stations have water in their tanks or that every ethanol mix will encounter water.
Rephrased statement (pink):
"With regards to the chemistry involved, it is a known fact that ethanol can absorb water from the air and through direct contact. This means that if there is water present in the fuel tanks at fuel stations, ethanol-containing fuels might come into contact with it. However, it is not accurate to assume that all fuel stations have water in their tanks, or that every ethanol mix will necessarily encounter water."