Knowledge Check Scope, Water, H-bonds

The main difference between prokaryotic and eukaryotic cells is the existence of _____ in eukaryotes.

Nucleus

When does a weak acid buffer best?

 

Within one pH unit of its pKa, both above and below.

 A buffer solution at pH 10 has a ratio of [HA]/[A−] of 10. What is the pKa of the acid?

11

How does the strength of hydrogen bonds compare with covalent bonds?

Hydrogen bonds are much weaker than covalent bonds.

The pKa values of the side chains of the common amino acids:

depend on the chemical nature of the side chain

Which of the following classes of compounds is hydrophilic?

Sugars and amino acids

The water molecule is polar because:

The hydrogen atoms are found on one "side" of the molecule.

Hydrogen is less electronegative than oxygen.

All of these are correct.

Electrons are not distributed symmetrically in the molecule.

The hydrogen atoms are found on one "side" of the molecule and hydrogen is less electronegative than oxygen.

Which will dissociate most in water, a weak acid or a strong acid?

STRONG acid

Bases are:

proton acceptors

Which of the following is a correct listing of electronegativity values, from low to high?

H, C, N, O

If atoms with greatly differing electronegativities form a bond, that bond will be:

polar

What is the isoelectric point (pI) for this amino acid titration curve? 

2.98

The tendency for an atom to attract electrons to itself in a chemical bond is called

electronegativity.

Which of these is true about weak acids and strong acids?

A strong acid has the greater Ka and lesser pKa.