Question

Please refer to data set D

do the following: 4. For the acid in Option_ drogen(s) with an asterisk a) Draw a Lewis structure o (*). (Hint: Organic acids, tho "HO2C-" or "-CO2H" written in a lewis structure of the acid and mark the acidic hydropen(s) with an aster ceanic acids, those composed of C, H, and O. will have the partial structure -.CO2H" written in the formula. In these cases, both oxveens are bonded to the hon and the hydrogen is bonded to one of the oxygen atoms) b) Draw a structure of the conjugate base of the acid you drew in 4a) c) Draw a structure of the conjugate base of the species for which you drew a structure in 4b) d) Which of the structures you've draw above (4a, 4b, or 4c) can act as both an acid and a base? Write appropriate chemical equations to explain your answer.

Answer 1

4.

a)

The chemical formula of the acid is .

Н.РНО,

P has 5 valence electrons.

Each O has 6 valence electrons , i.e. 3*6 = 18

Each H has one valence electron. i..e 1*3 = 3

Hence, total number of valence electrons in the molecule is 5+18+3 = 26

Now, we can draw the following Lewis structure with P as central atom.

:o : * H- P- 0- W -0 - I * acidic H

  

Note that P can have more than 8 electrons (expanded octet) around it as it has empty 3d orbital.

We can verify that our structure has 26 valence electrons by counting the bond pairs and lone pairs.

There are 7 bond pair and 6 lone pairs on O atoms. Hence, 13 bp+lp. Hence, total of 26 valence electrons.

The H atoms attached to O are acidic in nature as the electronegative O atom holds on to the bond electron pair making the deprotonation easier.

b)

The conjugate base of the above acid can be drawn by deprotonation of one of the acidic hydrogen.

H PHO3(acid) + H+ + HPH07 (con jugate base)

Hence, the Lewis structure of the conjguate base of the above acid in 4a) is

HP- :O : -I

c)

The structure in 4b) still has one more deprotonable H.

HPH07 (acid) + H+ + PHO-(conjugate base)

Hence, the conjugate base of the structure in 4b) can be drawn as

HP-

d)

Structure in 4b) acts as both an acid and as a base.

The equation in which it can act as a base is

H+ + HPH0, (base) = H,PHO3( conjugate acid)

The equation in which it can act as an acid is

HPH07 (acid) + H+ + PHO-(conjugate base)

This is possible because, structure in 4b) has one negative charge on O atom which can deprotonate an acid and thereby making the molecule a base. Also, it has a deprotonable H on it, hence, it can also act as an acid.

base part HP: ia : 0 :: acidic part