Question

An acid solution is 5.00% HCl by mass. Assuming that the density of the solution is 1.0 g/mL, find the molarity of the hydrogen ion in the solution. The molar mass of HCl is 36.5 g/mol

A.13.7

B. .73

C. 5.00

D. .365

E. 1.37

Answer 1

Ans : E

Solution:

Given that acid solution is 5.00% HCl by mass.

It means 5 g of HCl present in 100 mL solution

Therefore,

Mass of HCl = 5g

Molar mass of HCl = 36.5 g.mol^-1

Volume of HCl solution = 100 mL = 0.1 L

Then,

Molarity of HCl solution = (Mass of HCl / Molar mass of HCl ) x (1/ Volume of HCl solution in Litres)

= (5 g /36.5 g. mol^-1) x (1/ 0.1 L)

= 1.37 M

Molarity of HCl solution = 1.37 M

[HCl] = 1.37 M

[H+] = [HCl] = 1.37 M

Therefore, molarity of the hydrogen ion in the solution = 1.37 M