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.

What does x represent in the formula for the compound xcl4?

Which of the following electromagnetic waves can create ions?

Straightforward questions answered in the powerpoint slidesreaction: heating the starting materials under refluxwhat does it mean to heat under reflux? why do we choose water as the reflux solvent? what are boiling chips used for? why do we put a condenser on top of the reaction? why do we add heat and let the reaction stir for 30 minutes? why do we add sulfuric acid to the reaction after it cools as opposed to when it’s still hot? separation: filtration of precipitatewhy don’t we do an aqueous and organic extraction in the separatory funnel? why do you rinse the salicylic acid on the filter with ice cold water? purification: recrystallization of salicylic acid (no hot filtration needed)what is the difference in the amount of room temperature water vs. boiling water needed to dissolve the salicylic acid (assume a 1.2 gram yield of salicylic acid)? remember, in the lab if you need x ml of boiling water to dissolve a solid, then you should add a little more (definitely no more than 1.5 times the theoretical amount) to ensure it doesn’t recrystallize prematurely.analysis: melting point of salicylic acidwhat can you conclude if the melting point of the salicylic acid you just synthesized is 152-155oc and the 1: 1 mix of your product and “synthetic” salicylic acid is 151-154oc?