ammonium acetate buffer preparation
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Ammonium acetate is a chemical compound with the formula CH3COONH4 (or C2H4O2.NH3 or C2H7NO2). It is a white solid, which can be derived from the reaction of ammonia and acetic acid. It is available commercially and, depending on grade, can be rather inexpensive.
Uses and distinctive properties
- NH4C2H3O2 is occasionally employed as a biodegradable de-icing agent.
- It is often used with acetic acid to create a buffer solution, one that can be thermally decomposed to non-ionic products
- Ammonium acetate is useful in the Knoevenagel condensation in organic synthesis.
- It is relatively unusual example of a salt that melts at low temperatures.
- Can be used with distilled water to make a protein precipitating reagent.
- Is often used as an aqueous buffer for ESImass spectrometry of proteins and other molecules.
Ammonium acetate is volatile at low pressures. Because of this it has been used to replace cell buffers with non-volatile salts, in preparing samples for mass spectrometry. It is also popular as a buffer for mobile phases for HPLC with ELSD detection for this reason. Other volatile salts which have been used for this include ammonium formate.
CH3COONH4 is hygroscopic. It decomposes easily at elevated temperatures into acetamide.
- CH3COONH4â†’ CH3C(O)NH2 + H2O
In this reaction, a salt is converted to two molecular species, which is a relatively uncommon conversion at mild temperatures.
Acetate is a derivative of acetic acid. Two types of derivatives are known, salts and ester. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are acetates, which usually take the form of polymers. In nature, acetate is the most common building block for biosynthesis. For example, the fatty acids are produced by connecting C2 units derived from acetate.
Nomenclature and presentation of formula
When part of a salt, the formula of the acetate anion is written as CH3CO2−, C2H3O2−, and CH3COO−. Chemists abbreviate acetate as OAc− and AcO−. Thus, HOAc is the abbreviation for acetic acid, NaOAc for sodium acetate, and EtOAc for ethyl acetate.
The name for acetate, sanctioned by IUPAC, the international committee charged with naming chemical compounds, is ethanoate. This term is rarely encountered.
- CH3COOH CH3COO− + H+
Many acetate salts are ionic, indicated by their tendency to dissolve well in water. A commonly encountered acetate in the home is sodium acetate, a white solid that can be prepared by combining vinegar and sodium bicarbonate ("bicarb"):
- CH3COOH + NaHCO3â†’ CH3COO−Na+ + H2O + CO2
More specialized metal acetates can have complicated structures. Acetate is a relatively strong ligand in coordination chemistry. Examples of acetate complexes include chromium(II) acetate and basic zinc acetate.
Commercially important acetate salts are aluminium acetate, used in dyeing, ammonium acetate, a precursor to acetamide, and potassium acetate, used as a diuretic. All three salts are colourless and highly soluble in water.
Acetate esters have the general formula CH3CO2R, where R is an organyl group. The esters are the dominant forms of acetate in the marketplace. Unlike the acetate salts, acetate esters are often liquids, lipophilic, and sometimes volatile. They are popular because they have inoffensive, often sweet odors, they are inexpensive, and they are usually of low toxicity.
Almost half of acetic acid production is consumed in the production of vinyl acetate, precursor to polyvinyl alcohol, which is a component of many paints. The second largest use of acetic acid is consumed in the production of cellulose acetate. In fact, "acetate" is jargon for cellulose acetate, which is used in the production of fibres or diverse products, e.g. the acetate discs used in audio record production. Cellulose acetate can be found in many household products. Many industrial solvents are acetates, including methyl acetate, ethyl acetate, isopropyl acetate, ethylhexyl acetate. Butyl acetate is a fragrance used in food products.
Acetate in biology
Acetate is a common anion in biology. It is mainly utilized by organisms in the form of acetyl coenzyme A.
Intraperitoneal injection of sodium acetate (20 or 60 mg per kg body mass) was found to induce headache in sensitized rats, and it has been proposed that acetate resulting from oxidation of ethanol is a major factor in causing hangovers. Increased serum acetate levels lead to accumulation of adenosine in many tissues including the brain, and administration of the adenosine receptor antagonist caffeine to rats after ethanol was found to decrease nociceptive behavior.
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Answers:moles sodium acetate = 0.00500 L x 0.200 M =0.00100 moles acetic acid = 0.00700 L x 0.200 M=0.00140 total volume = 5.00 + 7.00 = 12.00 mL = 0.01200 L concentration sodium acetate = =0.00100 / 0.01200=0.0833M concentration acetic acid = 0.00140/ 0.01200=0.117 M pKa = 4.7 pH = 4.7 + log 0.0833/0.117=4.6
Answers:buffer solution is prepared by mixing a weak acid with its corresponding salt. acetic acid + sodium acetate got it dude if want various pH go for pH tablets
Answers:A buffer is a mixture of a weak acid and its conjugate base. In your case the weak acid is CH3COOH and the conjugate base is the acetate ion which comes from CH3COONa. Sodium acetate dissociates completely. CH3COOH <==> H+ + CH3COO- Ka = 1.8 x 10^-5 To make a buffer with a pH equal to pKa combine equal volumes of equimolar acetic acid and sodium acetate. The Henderson-Hasselbalch equation is often used to determine the pH of buffers with different concentrations of acid and conjugate base.
Answers:pH = pKa + log (base/acid) Henderson-Hasselbalch Eqn. The Ka of HC2H3O2 is 1.8 x 10^-5. Its pKa = 4.74. 5.2 = 4.74 + log (base/acid) 0.46 = log (base/acid) base/acid = 10^0.46 = 2.88 2.88 moles of base (NaC2H3O2) are needed for every mole of acid (HC2H3O2). The actual amounts of acid and base you would use depend on how much capacity you want the buffer to have. Just be sure to keep the ratio of moles of base to acid at 2.88/1. Examples: Suppose you want 1 L of buffer. You could measure out 2.88 moles of NaC2H3O2 and 1.00 mol of HC2H3O2 and add enough water to make 1 L. Or, if you didn't need as much buffer capacity, you could measure out 0.288 moles of NaC2H3O2 and 0.100 mol of HC2H3O2 and add enough water to make 1 L. This still keeps the ratio of base/acid at 2.88/1.