Question

0.90 g of hydrogen chloride (HCl) is dissolved in water to make 2.0 L of solution. What is the pH of the resulting hydrochloric acid solution

Answer 1

The pH of the resulting hydrochloric acid solution is 1.896

Step-by-step explanation:

pH, short for Hydrogen Potential, is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

The pH scale goes from 0 to 14. Values ​​less than 7 indicate the range of acidity and those greater than 7 indicate alkalinity or basicity. The value 7 is considered neutral.

pH is defined as the opposite of the base 10 logarithm or the negative logarithm of the activity of hydrogen ions or hydronium ions (H₃O)., whose equation is

pH = -log [H⁺] = -log[H₃O⁺]

Then you must know the concentration of [H⁺] or [H₃O⁺]

A strong acid is one that dissociates completely, therefore, a quantity of H + ions are transferred to the solution. Since HCl is a strong acid, then [HCl] = [H⁺]

Being molarity the number of moles of solute that are dissolved in a certain volume, it is defined as:

`molarity=(moles of solute)/(volume)`

So you must know the number of moles of HCl. Being its molar mass equal to 36.45
`(g)/(mole)`, then the following rule of three can be applied: if there are 35.45 grams of HCl in 1 mole, 0.9 grams of HCl in how many moles will they be?

`moles of HCl=(0.9 grams*1 mole)/(35.45 grams)`

moles of HCl= 0.0254

Then, being the number of moles of solute 0.0254 and the volume 2 L, the molarity is:

`molarity=(0.0254 moles)/(2 L)`

`molarity=0.0127(moles)/(L)`

Then, the concentration of [HCl] is 0.0127
`(moles)/(L)`. So [HCl] = [H⁺] = 0.0127
`(moles)/(L)`.

So the pH is calculated as:

pH = -log [H⁺]= -log 0.0127

pH= 1.896

The pH of the resulting hydrochloric acid solution is 1.896