Question

The weight of $HCl$ present in one liter of solution, if ph of the solution is:
A. 3.65 g
B. 36.5 g
C. 0.365 g
D. 0.0365 g

Answer 1

Hint: A Scale expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline. To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter.

Step by step answer: According to the definition of pH of solution is equal to -log of concentration of${H^ + }$ ion.
So according to this definition,
pH of the given solution of $HCl$ is equal to= 1
And ph is generally equal to =$ - \log \left[ {{H^ + }} \right]$
Therefore by putting values in above we get,
pH of given solution of $HCl$=$ - \log \left[ {{H^ + }} \right]$=1
$\Rightarrow$ $ - \log \left[ {{H^ + }} \right]$=1
Therefore we get, [ ${H^ + }$ ] = 0.1 molar
That is, the concentration of ${H^ + }$ ions is 0.1 molar in the given solution.
Thus 1 liter of solution contains 0.1 moles of $HCl$
And molarity of solution= no. of moles of solute present in one liter of solution,
Therefore, 0.1 moles of $HCl$ are present in one liter of solution.
Molecular mass of $HCl$= atomic mass of $H$ + atomic mass of $Cl$
$\Rightarrow$ (1+35.5) g/mole= 36.5g/mole
$\Rightarrow$Therefore 0.1 mole of $HCl$ will have molecular weight= 3.65g
Therefore there will be 3.65g of $HCl$ present in one liter of solution.

So the correct option is A.

Note: It must be noted that pH of solution is also equal to – log of {concentration of ${H_3}{O^ + }$] ions in a solution. Concentration of solution refers to its molarity. Both talk about concentration but one is having the aim of providing the scale of acidity or basic strength.