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yaroslaw [1]
3 years ago
6

The side chain of ________ has a pKa in the physiological pH range and is therefore often involved in proton transfer during enz

ymatic catalysis. The side chain of ________ has a pKa in the physiological pH range and is therefore often involved in proton transfer during enzymatic catalysis. His Glu Asp Arg

Chemistry
1 answer:
I am Lyosha [343]3 years ago
5 0

Answer:

Histidine (his)

Explanation:

Histidine (his), Arginine (arg), Aspartic acic (asp) and Glutamic acid (glu) have 3 acidic hidrogens each one, but only his has one physiological in the pH range.

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The answer is C. Arrhenius bases increase the concentration of OH- in solution.
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The vapor above a mixture of pentane and hexane at room temperature contains 35.5% pentane by mass. What is the mass percent com
FrozenT [24]
  • The mass percent of Pentane in solution is 16.49%
  • The mass percent of Hexane in solution is 83.51%

<u>Explanation</u>:

  • Take 1 kg basis for the vapor: 35.5 mass% pentane = 355 g pentane with 645 g hexane.
  • Convert these values to mol% using their molecular weights:

Pentane: Mp = 72.15 g/mol -> 355g/72.15 g/mol = 4.92mol

Hexane: Mh = 86.18 g/mol -> 645g/86.18 g/mol = 7.48mol

Pentane mol%: yp = 4.92/(4.92+7.48) = 39.68%

Hexane mol%: yh = 100 - 39.68 = 60.32%

Pp-vap = 425 torr = 0.555atm

Ph-vap = 151 torr = 0.199atm

  • From Raoult's law we know:  

Pp = xp \times Pp - vap = yp \times Pt                                       (1)

Ph = xh \times Ph - vap = yh \times Pt                                       (2)

  • Since it is a binary mixture we can write xh = (1 - xp) and yh = (1 - yp), therefore (2) becomes:

(1 - xp) \times Ph - vap = (1 - yp) \times Pt                                   (3)

  • Substituting (1) into (3) we get:

(1-xp) \times Ph - vap = (1 - yp) \times xp \times Pp - vap / yp            (4)

  • Rearrange for xp:

xp = Ph - vap / (Pp - vap/yp - Pp - vap + Ph - vap)      (5)

  • Subbing in the values we find:

Pentane mol% in solution: xp = 19.08%  

Hexane mol% in solution: xh = 80.92%

  • Now for converting these mol% to mass%, take 1 mol basis for the solution and multiplying it by molar mass:

mp = 0.1908 mol \times 72.15 g/mol

     = 13.766 g

mh = 0.8092 mol \times 86.18 g/mol

     = 69.737 g

  • Mass% of Pentane solution = 13.766/(13.766+69.737)

                                                       = 16.49%

  • Mass% of Hexane solution  = 83.51%
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3 years ago
When explaining about structural classifications to a group of students, the instructor discusses the peptides and proteins. The
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Answer:

There are approximately 200 amino acids.

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From Ohm's law, we get the general equation that would relate the voltage, current, and resistance,
                                  V = I x R
where V is voltage, R is resistance, and I is current. Deriving the equation for R
                                       R = V / I
                              R = (1.5 volts) / (0.7 amps) = 2.14 Ohms
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