At pH 6.0 the N-terminus of His-His-His-His would have a (positive/ negative) charge. The C-terminus would have a (positive/ negative) charge. Since the pKa for His is 6.0, essentially half of the residues would carry a (negative/ positive) charge on their side chains, so that the charge per residue could be considered to be (+2.0/ +0.5 / +1.0/ +1.5). The result would be a net charge on the tetrapeptide of (+2.0/ -1.0/ +1.0/ -2.0). The tetrapeptide would be (more/ less) soluble in water than Histidine itself. When the bonds are formed between the carboxylate and amino groups to form the tetrapeptide, the groups that would interact with water are lost.

Enough of a monoprotic weak acid is dissolved in water to produce a 0.0172 m solution. if the ph of the resulting solution is 2.39 at 20 °c, determine the pka for the acid.

Using data from seismic waves, geologists have learned that earth’s interior is made up of several

The last few miles of the marathon are the most difficult for heather, her hair plastered to her head, sweat clinging to her arms, and her legs already feeling as if they had nothing left, just dead weight. after grabbing a cup of ice water, she feels the ice cubes smash against her nose as she gulps some cool refreshment and keeps on running. in these last few miles, the breeze kicks up and she finally feels some coolness against her skin. drips of sweat, once clinging to her forehead, now spill down, and heather feels more pain as the sweat flows into her eyes. which of the following is the most likely reason why the ice struck heather’s nose when she took a drink? a) water can function as a solvent. b) water can store large amounts of heat. c) water can moderate temperatures through evaporative cooling. d) the density of water decreases when it freezes. e) water has a cohesive nature. sweat remained on heather’s forehead and arms because of the a) high salt content of sweat b) cohesive nature of water c) ability of water to moderate heat d) high evaporative cooling effect of water e) ability of water to act as a solvent