Chapter 23, Problem 2TC

Rank the following molecules in order of increasing molecular mass: cholesterol, glycine, deoxyribonucleic acid.

To determine

The order of increasing molecular mass in the following molecules: cholesterol, glycine, deoxyribonucleic acid.

Answer to Problem 2TC

The order of increasing molecular mass is $\text{Glycine}<\text{Cholesterol}<\text{Deoxyribonucleic acid}$

Explanation of Solution

Cholesterol is basically a lipid. The molecular formula of cholesterol is ${\text{C}}_{27}{\text{H}}_{46}\text{O}$

The molecular mass of cholesterol can be calculated as,

$\begin{array}{c}\text{Molecular}\text{mass}=\left(27\times 12+46\times 1+16\right)\text{g}/\text{mol}\\ =386\text{g}/\text{mol}\end{array}$

The glycine is considered as amino acid and the molecular formula of glycine is ${\text{C}}_2{\text{H}}_{\text{5}}{\text{NO}}_{\text{2}}$

$\begin{array}{c}\text{Molecular}\text{mass}=\left(2\times 12+5\times 1+1\times 14+2\times 16\right)\text{g}/\text{mol}\\ =75\text{g}/\text{mol}\end{array}$

The deoxyribonucleic acid gets considered as nucleic acid and the molecular formula of deoxyribonucleic acid is ${\text{C}}_{15}{\text{H}}_{31}{\text{N}}_3{\text{O}}_{13}{\text{P}}_2$

$\begin{array}{c}\text{Molecular}\text{mass}=\left(15\times 12+31\times 1+3\times 14+13\times 16+2\times 31\right)\text{g}/\text{mol}\\ =523\text{g}/\text{mol}\end{array}$

Thus, the molecular mass of deoxyribonucleic acid is highest. And the molecular mass of cholesterol is greater than glycine. The order of increasing molecular mass is, $\text{Glycine}<\text{Cholesterol}<\text{Deoxyribonucleic acid}$

Conclusion:

Therefore, theorder of increasing molecular mass is $\text{Glycine}<\text{Cholesterol}<\text{Deoxyribonucleic acid}$