chem q's

[jaja]

Q1)
at ph 6, the amino acids glycine, glutamic acid, asparagine and histidine exist in their fully charged form. Which amino acid would migrate the furthest towards the positive terminal in gel electrophoresis?...

i don't get this question because the ph at which amino acids exist as zwitterions depends upon the z group... where does that tell us??

Q2)300ml of .35M  Ca(oh)2 solution was reacted with 300 ml of 0.4 M  HCL. the ph of the resultant solution is closest to???

Q4) is NH4 N02 oxidation number for Nitrogen +-3??? how??

Q5)Monosaccharids behave as weak reducatants?? explain

[Mao]

Q1, the pH given is the pH of the environment, i.e. not purely because of the amino acids. In this case, given that all the amino acids are in their fully charged form, the separation of these in gel electrophoresis depends on their mass. (Think back to how gel electrophoresis is used for DNA fingerprinting)

Q2
remember that the ionic constant of water is 10^-14, that is,
In this case, the resulting solution will be 600mL, reaction of the two chemicals would give:

n(OH-) = 0.3 * 0.35 * 2 = 0.21 mol
n(H+) = 0.3 * 0.4 = 0.12 mol
n(OH-)_excess = 0.09 mol
c(OH-)_final = 0.09 / 0.6 = 0.15 M
hence, 0.15 * c(H+) = 10^-14, work out c(H+), the pH of the solution will be

4 NH₄NO₂ is an ionic compound, of NH₄⁺ (oxidation number = -3), and NO₂^- (oxidation number = +3)

5
Monosaccharides (and dissacharides and polysaccharides) do behave as reductants, as they are 'oxidised' by air when combusted.

in C6H12O6, the carbon has oxidation number of 0, when burnt in air, the carbon is present as CO2, oxidation number is +4, hence has been oxidised (i.e. act as reductant)

[dekoyl]

Q1, the pH given is the pH of the environment, i.e. not purely because of the amino acids. In this case, given that all the amino acids are in their fully charged form, the separation of these in gel electrophoresis depends on their mass. (Think back to how gel electrophoresis is used for DNA fingerprinting)

In the answer, it talks about asparagine forming a positively charged molecule and glycine and histidine forming a neutrally charged molecule. It is because glutamic acid will form a negatively charged molecule, it will move towards the positive terminal.

It might completely missed it (knowledge not deep) but why don't they mention mass?

Thanks