Question

Glycine in its zwitterion form is shown in the following figure. Its central carbon atom is bonded to four groups, namely, two H atoms, positively charged NH3 group and a carbon, that is double-bonded to oxygen and bonded to another negatively charged oxygen.

Part B pH 12.0 Draw the molecule on the canvas by choosing buttons from the Tools (for bonds), Atoms, and Advanced Template toolbars, including charges where needed.

Part C pH 6.0 Draw the molecule on the canvas by choosing buttons from the Tools (for bonds), Atoms, and Advanced Template toolbars, including charges where needed.

Answer 1

Solution:

Part A) Glycine at pH=12, exists in anionic form as:

NH2 -CH2-COO-

Glycine in basic medium, lost a proton and converted into carboxylate anion as:

NH2-CH2-COOH - H+ = NH2-CH2-COO-

Part B) Glycine at pH=6, exists in cationic form as:

+NH3-CH2-COOH

In acidi medium NH2 group accept a proton and converted into NH3+ as:

NH2-CH2-COOH + H+ = +NH3-CH2-COOH