A mixture of lipids is applied to a silica gel column and the column is washed with increasingly polar solvents. The mixture consists of phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine, cholesteryl palmitate (a steryl ester), sphingomyelin, palmitate, n-tetradecanol, triacylglycerol, and cholesterol. In what order will the lipids elute from the column from the first to elute from the column to the last

Explanation:

Silica gel is polar, therefore the non-polar (hydrophobic) lipids will elute first whereas the polar (hydrophilic) lipids will elute later. In the given lipid sample the order from non-polar to polar is:

triacylglycerol, cholesterol, sphingomyelin, phosphatidylserine.

Hence the order of elution from the first to the last will also be the same. i.e,triacylglycerol( elutes1st), cholesterol, sphingomylein, phosphatidylserine (elutes last).

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years

ill try to . no promises tho.

explanation: