Briefly explain the difference between the pairs of terms below: a)D-/L- (as in

Question

Briefly explain the difference between the pairs of terms below:

a)D-/L- (as in isomers)

b)Saturated/unsaturated

c)Proton/electron

d)Compound/mixture

e)Osmosis/dialysis

Chiral compounds occur when a carbon atom has four different things bonded to it. All but the simplest amino acids (glycine) are chiral because the alpha carbon has an amine group, a carboxylic acid group, and two different groups bonded to it. Some amino acids are even more complicated in that another carbon in the molecule is also chiral. Look at the table of the 20 common amino acids and name 2 amino acids that have a second chiral carbon atom.

Salt lowers the freezing point of water. So will sugar. If one tablespoon of solid (salt or sugar) is dissolved in ¼ cup of water, which material, salt or sugar will lower the freezing point of the water by the greater amount? What two facts most explain the difference?

Discuss the difference between the Maillard reaction and caramelization. Distinguish them according to the ingredients they require and the conditions needed.

Explanation / Answer

ANSWER
Q1.

(a) D and L notations represent the relative configuration of a compound in relation to glyceraldehyde. Glyceraldehyde has on chiral centre. S-glyseraldyde is labelled as L and R-glyceraldehyde as D. The compound with one stereocentre is labelled as L / D depending upon the disposition of groups in relation to glyceraldehyde. If compound has more than one stereocenters than last stereocenter is choosen

(b) Saturated/Unsaturated: A compound having one or more C-C multiple bonds is called unsatured e.g ethene, ethyne etc. If there exist onlt C-C single bonds the compound is saturated.

(c) Proton/electron: These are subatomic paticles.Proton has a mass of 1.6727 X 10-24g and a chare of +1 unit.

electron has a charge of -1 unit and mass of 9.11 X 10-28g.

(d) Compound/Mixture: Compound is the stable combination of two or more elements combined in fixed proportion. the components of the compound can not be separated by physical processes. However a mixture has components present in any proportion , which can be separated by physical precess like evaporation etc.

(e) Osmosis/Dialysis: Osmosis is the movement of solvent molecules from lower concentrato higher concentration through a semipermeable membrane (SPM) as solute molecules can not pass through semipermeable membrane. While as in some cases some solute molecules can pass throuh SPM hence move from higher concentratio to lower concentration. So Osmosis is movement of solvent molecules across SPM and dialysis is movement of solute particles across SPM.

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