Qualitative Solubility Predictions

[ncm2]

Homework Statement

Which solvent would be a better choice to dissolve each of the following?
Tetracholride or Water
a - thiamine hydrochloride
b - CH3(CH2)16CO2H
c - C6H12
d - CS2
e - NH3
f - (NH4)(CH3CO2)

Homework Equations

Draw the structure and find polarity
Like dissolve like

The Attempt at a Solution

I know water is polar, so will be soluble with other polar molecules
I know tetrachloride is nonpolar, soluable with non polar.

a - thiamine hydrochloride - Polar b/c Vitamin B and C are water soluable, and structure
b - CH3(CH2)16CO2H - Polar b/c CO2H end of chain
c - C6H12 - non polar
d - CS2 - non polar because structure
e - NH3 - polar
f - (NH4)(CH3CO2) - polar b/c CH3CO2

Clearly I have gone somewhere as the answer is wrong. I really don't know if F is right. And also B because it is a long chain of C-H which are not polar.
I have also tried with B and F as non-polar and that's wrong too.

 

[chemisttree]

I assume that you must get all of them right or the program marks the entire problem as wrong.

Only one of your answers is wrong, not two. 'F' is ammonium acetate... a salt. Polar or non-polar?

 

[Blueshift5]

it is important to base your predictions on scientific principles and evidence rather than assumptions or previous knowledge. In this case, the solubility of a substance in a particular solvent depends on the intermolecular forces between the solute and solvent molecules. Therefore, simply considering the polarity of a molecule may not always accurately predict its solubility.

To determine the best solvent for each substance, one must consider the structure and functional groups present in each molecule. For example, thiamine hydrochloride contains both polar and nonpolar functional groups, so it may have some solubility in both water and tetrachloride. However, the polar functional groups (such as the hydroxyl and amine groups) will likely make it more soluble in water due to the presence of hydrogen bonding.

Similarly, CH3(CH2)16CO2H may have some solubility in both water and tetrachloride due to the presence of both polar and nonpolar functional groups. However, the polar carboxylic acid group will likely make it more soluble in water.

C6H12 is a nonpolar molecule and will likely be more soluble in tetrachloride than in water.

CS2 is a nonpolar molecule and will likely be more soluble in tetrachloride than in water.

NH3 is a polar molecule and will likely be more soluble in water than in tetrachloride.

(NH4)(CH3CO2) is a polar molecule due to the presence of the NH4+ ion and the polar CH3CO2- ion. It will likely be more soluble in water due to the polar functional groups and the ability of water to form hydrogen bonds with these groups.

In summary, while polarity can be a useful factor to consider when predicting solubility, it is important to also consider the specific functional groups and intermolecular forces present in a molecule to accurately predict its solubility in a particular solvent.