1. Answer the following questions regarding the acid- base reaction described be

Question

1. Answer the following questions regarding the acid- base reaction described below:

In a mixture containing 2.6 g of propanoic acid and 2.2 g of acetanilide (MW CH3CH2COOH= 74 g/mol, KOH= 56 g/mol, volume of CH2Cl2 used = 26 mL)

a. Name an organic solvent that could be used to dissolve the mixture prior to separation of the mixture by extraction with KOH. (dichloromethane?)

b. What volume of 2M KOH will be required to completely extract the propanoic acid from the mixture. (Assume the entire mixture is contains propanoic acid)

2. Write the equation for the reaction of propanoic acid with KOH.

3. Is Acetanilide an acid or a base or neither? Neither?

Explanation / Answer

2.The acid (propionic acid) and base (KOH) will react to give the potassium salt of the acid and water:

CH3CH2C(O)OH + KOH --> CH3CH2C(O)OK + H2O

3.it's neither an acid nor a base because Compared to amines, amides are very weak bases. While the conjugate acid of an amine has a pKa of about 9.5, the conjugate acid of an amide has a pKa around -0.5. Therefore amides don't have as clearly noticeable acid-base properties in water. This lack of basicity is explained by the electron-withdrawing nature of the carbonyl group where the lone pair of electrons on the nitrogen is delocalized by resonance. On the other hand, amides are much stronger bases than carboxylic acids, esters, aldehydes, and ketones (conjugated acid pKa between -6 and -10).

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