BIOC Chapter 2

which has the greater Ka, a weak acid or a strong acid?

a strong acid

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

a strong acid

which has a greater pKa, a weak acid or a strong acid?

a weak acid

which of the following molecules will not form hydrogen bonds? a) CH4 b) NH3 c) H2O d) HF

a) CH4

which of the following is not true? a) a buffer is a solution which maintains a solution at a neutral pH b) buffer solutions are made to resist change in pH c) zwitterion buffers are less likely to interfere with biological reactions than non-zwitterions d) HEPES is a zwitterion buffer

a) a buffer is a solution which maintains a solution at a neutral pH

which of the following characteristics makes for a good hydrogen bond donor? a) high electronegativity b) a nonbonding pair of electrons c) both of the above d) neither of the above

a) high electronegativity

bases

are proton acceptors

which of the following molecules has polar bonds but is itself is not polar? a) NH3 b) CO2 c) CH4 d) H2O

b) CO2

which of the following compounds is hydrophobic? a) table salt b) cholesterol c) phosphate esters d) cholesterol and phosphate esters e) all of these are hydrophobic

b) cholesterol

which of the following statements about hydrogen bonds is false? a) the donor is a hydrogen atom bonded to a less electronegative atom than hydrogen b) the more linear the bond, the stronger the interaction c) the acceptor must contain a non-bonded pair of electrons d) it is a type of non-covalent bond

a) the donor is a hydrogen atom bonded to a less electronegative atom than hydrogen

which of the following is true about ionic compounds? a) they are more likely to dissolve in non-polar solvents than covalent compounds b) they always dissolve completely in water c) they never dissolve in polar solvents d) some of them dissolve completely in water or other polar solvents, while others do not

d) some of them dissolve completely in water or other polar solvents, while others do not

which of the following classes of compounds is hydrophilic? a) sugars b) fatty acids c) amino acids d) sugars and amino acids e) all of these

d) sugars and amino acids

which of the following is true regarding hydrogen bonds? a) they can only form between two different molecules b) they are important in protein folding but not DNA structure c) they are important in DNA structure but not protein folding d) they can be found within a single molecule

d) they can be found within a single molecule

ionic compounds and polar covalent compounds tend to dissolve in water because of

ion-dipole and dipole-dipole interactions

a buffer solution

is used to control the pH of a solution

hydrogen bonds

play an important role in the solvent properties of water

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

polar

which of the following molecules is polar? a) CCl4 b) CH4 c) CO2 d)NH3 e) none of these molecules is polar

d) NH3

which of the following has the highest electronegativity? a) C b) H c) N d) O e) P

d) O

many of the properties of water can be accounted for by the fact that a) it is polar b) it forms hydrogen bonds c) it is a bent molecule d) all of these are true

d) all of these are true

which of the following is a true statement? a) most substances contract when they freeze b) water expands when it freezes c) hydrogen bonding is related to water's tendency to expand as it freezes d) all of these are true

d) all of these are true

which of the following molecules is amphipathic? a) sodium chloride b) acetic acid c) benzene d) palmitic acid

d) palmitic acid

which of the following compounds is most likely to form a micelle? a) acetic acid b) glucose c) glycerol d) sodium palmitate e) sodium phosphate

d) sodium palmitate

what is the maximum number of hydrogen bonds a single water molecule can form?

4

list the following in a correct listing of electronegativity values, from low to high C, H, O, N

H, C, N, O

the main blood buffer system is

H2CO3/ HCO3-

buffers which lack biological activity and are unlikely to interfere with any biochemical reactions include

Tris and HEPES

is water an acid or base?

both

true hydrogen bonds can not form between hydrogen and this element: a) N b) F c) C d) O e) all of these elements can form hydrogen bonds

c) C

which of the following characteristics makes for a good hydrogen bond acceptor? a) a high electronegativity b) a nonbonding pair of electrons c) both of these d) neither of these

c) both of these

molecules which contain both hydrophilic and hydrophobic regions are: a) amphipathic b) detergents c) able to form micelles d) both amphipathic and detergents e) all of these

e) all of these

the water molecule is polar because: a) electrons are not distributed symmetrically in the molecule b) the hydrogen atoms are found on one "side" of the molecule c) hydrogen is less electronegative than oxygen d) the hydrogen atoms are found on one "side" of the molecule and hydrogen is less electronegative than oxygen e) all of these are correct

e) all of these are correct

which of the following is important to know when deciding if a given buffer will be effective for an experiment? a) the pKa of a buffer compound b) the buffer capacity c) the concentration of the buffer d) whether the experiment is likely to generate hydrogen ions or hydroxide ions e) all of these are important considerations

e) all of these are important considerations

hydrogen bonds explain which of the following properties of water? a) water is a great solvent for all ionic and polar molecules b) water has high melting and boiling points for its small size c) ice expands when frozen d) both the abnormal melting and freezing points and that ice expands when frozen e) hydrogen bonds explain all of these properties

e) hydrogen bonds explain all of these properties

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

electronegativity

a micelle is a structure which

has its polar groups on the outside and non-polar groups on the inside when in water and explains how soaps and detergents work

the non-covalent interaction below associated with the strongest force in aqueous solution is

hydrogen bonding

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

hydrogen bonds are much weaker than covalent bonds

the substance most likely to form a micelle is

sodium palmitate

buffer capacity refers to

the extent to which a buffer solution can counteract the effect of added acid or base

in a titration of a weak acid by a strong base

there is a region in which the pH changes slowly

nonphysiological buffers such as HEPES and PIPES have come into common use because

they have less tendency to interfere with reactions

how do hydrogen bonds tend to affect the melting and boiling points of substances?

they tend to increases both melting and boiling points

in a hydrogen bond

three atoms lie in a straight line

hydrogen bonds can only form when the hydrogen atom is involved in a polar bond

true

the inflection point of the titration curve for a weak monoprotic acid is equal to its pKa

true

when does a weak acid buffer best?

within one pH unit of its pKa, both above and below