Lec.7 Eman

Question 1

What is the primary reason for the preservative action of weak acids in oil-water systems?
a) The ionic form of the acid
b) The polar portion of the acid
c) The unionized form of the acid
d) The hydrogen ion concentration

Answer 1

c) The unionized form of the acid

Question 2

What is the main reason for the ease of penetration of unionized acids into living membranes?
a) Their polar nature
b) Their ionic nature
c) Their large nonpolar portion
d) Their solubility in water

Answer 2

c) Their large nonpolar portion

Question 3

Where are bacteria typically located in oil-water systems?
a) Only in the oil phase
b) Only in the water phase
c) Only at the interface between oil and water
d) Both in the water phase and at the oil-water interface

Answer 3

d) Both in the water phase and at the oil-water interface

Question 4

What factors determine the distribution of benzoic acid between the oil and water phases in an oil-water system?
a) The distribution coefficient, Ka, and the phase volume ratio
b) The dissociation constant, Ka, and the phase volume ratio
c) The distribution coefficient, Ka, and the hydrogen ion concentration
d) The dissociation constant, Ka, and the hydrogen ion concentration

Answer 4

b) The dissociation constant, Ka, and the phase volume ratio

Question 5

What is the total concentration of benzoic acid that must be added to preserve an oil-water system (peanut oil and water)?
a) The concentration of monomer benzoic acid
b) The concentration of dimer benzoic acid

Answer 5

a) The concentration of monomer benzoic acid

Question 6

What is the total concentration of benzoic acid that must be added to preserve an oil-water system in non-polar solvents?
a) The concentration of monomer benzoic acid
b) The concentration of dimer benzoic acid

Answer 6

b) The concentration of dimer benzoic acid