Answer : The pH of the solution is, 1.31
Explanation : Given,
Mass of [tex]HCl[/tex] = 248 mg = 0.248 g (1 mg = 0.001 g)
Volume of solution = 140 mL
Molar mass of [tex]HCl[/tex] = 36.5 g/mole
First we have to calculate the concentration of hydrochloric acid.
Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.
Formula used :
[tex]\text{Molarity}=\frac{\text{Mass of }HCl\times 1000}{\text{Molar mass of }HCl\times \text{Volume of solution (in mL)}}[/tex]
Now put all the given values in this formula, we get:
[tex]\text{Molarity}=\frac{0.248g\times 1000}{36.5g/mole\times 140mL}=0.0485mole/L=0.0485M[/tex]
The concentration of HCl is, 0.0485 M
As we know that, HCl dissociates to give hydrogen ion and chloride ion.
The dissociation reaction is:
[tex]HCl\rightarrow H^++Cl^-[/tex]
Concentration of HCl = Concentration of H⁺ = Concentration of Cl⁻ = 0.0485 M
Now we have to calculate the pH of the solution.
pH : It is defined as the negative logarithm of hydrogen ion concentration.
Mathematically,
[tex]pH=-\log [H^+][/tex]
[tex]pH=-\log (0.0485)[/tex]
[tex]pH=1.31[/tex]
Therefore, the pH of the solution is, 1.31