Question

A diprotic acid is composed of carbon, hydrogen and oxygen. It is 60.6% C, and 3.58% H by mass. A titration requires 25 mL of 0.850MNaOH to neutralize 5.692g of the acid. What is the molecular formula for diprotic acid?

a- C27H19012

b- C54H38024

c- C22H20O13

d- C12H15O4

e- C15H12O4

Answer 1

The molecular formula for diprotic acid is :

a)- C27H19012

Step-by-step explanation:

It is given in the question that :

The titration requires 25 mL of 0.850M NaOH to neutralize 5.692g of the acid.

1.Calculate Moles of NaOH,

M = 0.850 M

V = 25 mL

`Molarity=(moles)/(Volume(ml))* 1000`

`0.850=(moles)/(25)* 1000`

`moles =(0.850)/(1000)* 25`

Moles of NaOH = 0.02125

2. Calculate the moles of Acid

But, moles of diprotic acid = moles of NaOH

Since it is a diprotic acid it require 2 mole of NaOH (Diprotic gives 2H+)

So,

Moles of Acid required for neutralisation = 1/2 moles of NaOH

moles of Acid =

`(1)/(2)moles\ of\ NaOH`

`(1)/(2)* 0.02125`

Moles of Acid = 0.010625

3.Calculate the molar mass of Acid

Mass = 5.692 g

`Moles = (mass)/(Molar\ mass)`

`0.010625 = (5.692)/(Molar\ mass)`

`Molar\ mass = (5.692)/(0.010625)`

Molar mass = 535.71 g

4.Check from the options which has Molar mass = 535 gram or around

a)C27H19012

= 27(mass of C) + 19(mass of H) + 12(mass of O)

= 27(12) + 19(1) + 12(16)

= 324 + 19 + 192

= 535 gram

Hence , A is correct option.