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What Is an Acetate?

Sodium acetate can be used to give a vinegar flavor to potato chips.
Nail polish remover containing acetate.
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  • Written By: Vincent Summers
  • Edited By: Jessica Seminara
  • Last Modified Date: 10 October 2014
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An acetate is a chemical compound derived from acetic acid, or ordinary household vinegar, the fermentation product of wine. The acid’s chemical structure consists of a methyl group (CH3) bonded to a carboxylic acid group (COOH). When acetic acid’s carboxylic acid hydrogen is stripped, the remainder, CH3COO-, is called "acetate" (shorthand, -Ac). There are both organic and inorganic forms of acetate. An example of the former is the ethyl ester, or oily fingernail polish remover, while sodium is an inorganic acetate. One of the best known and commercially most important polymers is the plastic polyvinyl acetate (PVA).

These acetic acid derivatives find very diversified applications. Along with its most important use as a buffering agent, sodium acetate can be found in a hospital setting, where it is used in the intravenous treatment of the low-sodium metabolic condition, hyponatremia. It is widely used as a flavoring agent in foods, including convenience treats, such as salt and vinegar potato chips. Interestingly, the same compound may be used to make an unusual form of hand warmer or heating pad. In waste handling, sodium acetate is used to neutralize acidic sulfuric acid contaminated water by means of the exchange reaction: NaAc + H2SO4 → Na2SO4 + HAc, or sodium acetate plus sulfuric acid gives sodium sulfate plus acetic acid.

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A class of very important chemical reactions in nature is the acetate biosynthesis reaction. In this process, the chemical complexity of molecules is increased through the enzymatic addition of molecules of acetic acid, generally mediated by bacteria. This process is invoked to replace certain more costly synthetic reactions, particularly in the flavor industry. One example is the production of banana oil, which can be manufactured utilizing an engineered bacterium, Esicherichia coli. Just understanding the process is also proving valuable, enabling successful ongoing research into the preservation of delicate strawberry esters through the use of controlled atmosphere (CA).

Cellulose nitrate was once the standard film variety used by the motion picture industry — up until about the 1940s. That substance is unstable and highly flammable; cellulose nitrate fires are difficult to extinguish and produce dangerous gases, including corrosive nitrogen oxides and carbon monoxide. Many important films produced on cellulose nitrate have been forever lost due to degradative oxidation. More recent film stock employs cellulose acetate, the so-called "safety film." Unfortunately, even this improved film is subject to degradation, though it can be preserved for more than a century if stored under cold, dry conditions.

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anon356491
Post 5

I have a chemistry related question about sodium acetate. How would you calculate the electronegativity of the acetate molecule, and then, how would you calculate the electronegativity of the entire sodium acetate compound?

FrameMaker
Post 4

@GiraffeEars- I will take a stab at answering your last few questions. A Bronstead-Lowry acid is essentially a proton donor. A Lewis acid is a substance that can accept a pair of electrons.A Lewis base, like acetate, can give up a pair of electrons. A Lewis base will have a neutral or negative charge, and usually contains an element with lone electron pairs; elements like oxygen, nitrogen, and halogens.

A Lewis acid will have a neutral or positive electron charge. Taking all of this into account, mixing a Lewis acid with a Lewis base no protons are donated or accepted. This creates a movement of electrons rather than a movement of protons.

cougars
Post 3

@GiraffeEars- I will try to explain the oxy acids to you so I can answer your question about oxidation and acid strength. Basically, the higher the bond strength in the oxy-acid, the stronger the oxy-acid is. The bond strength dictates how easily protons dissociate (leave) an acid. Thus, you can conclude that acid strength increases with the electro-negativity of the molecule. A higher electro-negativity translate to a weaker bond, thus the acid is intrinsically stronger.

To put this into perspective, the acid will be stronger when there are more oxygen atoms in the acid (if the cation is the same). For example, HClO3 is stronger than HClO, but is weaker than HClO4. This works because the greater the number of oxygen’s, the greater the electro-negativity of the atom, so the stronger the molecule pulls on other hydrogen atoms.

submariner
Post 2

@GiraffeEars- Oh the days of acid base equilibrium… I remember struggling through those lectures and labs myself. I can help fill you in on some of the things you are asking. It will be somewhat nice to dust off some of the old chemistry knowledge stored in my brain.

For your first question: acetate is a weak Bronstad base. The Kb value of this base is ten orders of magnitude higher than water (I think), meaning it has a higher pH than water. To determine the pH of an acid or base, you simply take the negative logarithm of your Kb or Ka value. For acetate, the pH is somewhere around 9.5, making it a little more basic than seawater.

The conjugate acid to acetate is acetic acid (a.k.a. Vinegar). This means that when you react acetate with water (an autoionizing molecule) you form hydroxide ion and vinegar as products.

The difference between this base ionization and an acid ionization is quite simple. An acid ionizes with water to form hydronium and its conjugate base. To put this into context, acetic acid (the conjugate of acetate) forms the hydronium and acetate as products. This is simply the reverse of the Bronsted base reaction I explained earlier. I hope I was able to simplify the first paragraph of questions for you. I will let someone else attempt to answer the rest.

GiraffeEars
Post 1

I have a few chemistry related questions that I was hoping someone could answer for me. Is acetate a base or an acid? If Acetate is a base, is it a strong, weak, or neutral base? If acetate is an acid, is it a strong, weak, or neutral acid? How do I know if acetate is an acid or a base? What is the product of a base ionization and an acid ionization?

How do I relate the Ka constant of a Bronsted-Lowry acid to the Kb constant of a base? How do the Bronsted-Lowry acids and bases relate to the Lewis Acids and bases? Finally, what does oxidation have to do with the strength of acids and bases?

I know this is a lot to ask, but I am really having trouble in my general chemistry class. We are discussing the Bronsted-Lowry and Lewis acids and bases. This is the hardest stuff I have done in chemistry yet, and I would like a sound understanding of the basic subject matter of this section. Thank you to any chemistry buffs out there that can lend me his or her time.

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