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Answers:The "carbonic acid" system: CO2(aq) + H2O <==> H+ + HCO3- -- Ka = 4.3 x 10^-7 You will notice the absence of H2CO3. That is because there is no H2CO3. As a molecule, It does not exist in aqueous solution. What we have called carbonic acid in the past is the equilibrium system of carbon dioxide, water, hydrogen (hydronium) ions and bicarbonate ions. Clearly, it is a good buffer system because evolution has selected it to maintain the pH of our blood. The Henderson-Hasselbalch equation is an equation which approximates the pH of a buffer system based on the concentrations of a weak acid and its conjugate base, and the assumption that concentration of the undissociated acid does not change. pH = pKa + log([base]/[acid])
Answers:Well, I'm bad at Chemistry but I can do a partial, concept answer. A buffer is a chemical which stabilizes pH, so whether acid or base is added, the pH will tend to bend towards the original value. Sorry, I can't complete the question. An example of a buffer: In order to stabilize the pH in blood, the body has an organic buffer of HCO, which can decompose into HCO- and H+ in response to a drop in pH and can recompose to HCO for a rise in pH. Since pH is a measure of the proton concentration (H+), the addition or removal of H+ changes the pH.
Answers:Amino acids are zwitter-ions, meaning they can have charges on both the amino & carboxylic groups, and yet have no net charge. Confused? wait! The amino group, -NH2 can become -NH3+, while the carboxylic group -COOH becomes -COO-. This is the zwitter ion. This is the form that predominates at ambient conditions. When in acidic media, the -COO- group grabs a proton, becoms -COOH and gets rid of the H+. The amino acid now has a net positive charge, (fully protonated, two protons at both acid & amino ends), so we call it the protonated form. In basic media, the -NH3+ group donates a proton to the medium (with extra OH-), to form H2O, thus getting rid of extra OH-. The amino acid now bears a net negative charge, so we call it anionic form. This is known as pseudo-buffer action. You should also be aware that although amino acids show this behaviour, it is limited and amino acids themselves are not classified as buffers.
Answers:C) I would imagine that it is because we produce more acids; the carbon dioxide from metabolism forms carbonic acid in the plasma which needs to be buffered.