Match each of the following carboxylic acids to their appropriate pKa values (5.0, 0.2 and 2.7): (A) FCH2COOH (B) (CH3)3CCOOH (C) CF3COOH

Explanation:

Higher the acidic strength  , lower the pKa value.

Among the given acids , CF₃COOH is most acidic because of 3  fluorine atom attached with carbon . fluorine is highly electro-negative electron withdrawing group .

So , acidic strength of given acids will decrease as follows

CF₃COOH > FCH₂COOH > (CH3)₃CCOOH

Hence CF₃COOH will have least pka value ie 0.2

pka value of FCH₂COOH will be 2.7

pka value of (CH3)₃CCOOH will be 5.0

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.