) An organic chemistry lab book gives the following solubility data for oxalic acid 9.5g/100ml water 23.7g/100ml ethanol 16.9g/100ml ether (a) A 14CL student has 40 g of oxalic acid in 1000ml of water and wishes to extracted into an organic solvent for further experiments. Which solvent should the student use for the extraction

Ethanol

Explanation:

Solvent extraction is the process in which a compound transfers from one solvent to another owing to the difference in solubility or distribution coefficient between these two solvents(Science Direct).

We have to remember that oxalic acid will be extracted better into a solvent in which it is more soluble. From the data given; oxalic acid is more soluble in ethanol than in ether.

This simply means that ethanol is a better solvent for extracting oxalic acid  from water when compared to ether.

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