Question

If sulphuric acid solution has pH = 2 then its molarity is______.
1. 1/100
2. 1/50
3. 1/2
4. 1/200

Answer 1

Correct Answer - Option 1 : 1/100

The correct answer is 1/100.

• pH is defined as the negative logarithm to the base 10 of the hydrogen concentration of the solution.

Given that the pH of the solution is 2, we can write that

⇒log ( H+ ) = 2

We know that log 10 = 1

We also know that n log b = log bⁿ

⇒ log 10² = 2 log 10

⇒ log 10² = 2 × 1

⇒ log 10² = 2

This means we can write :

⇒ log ( H+ ) = log 10²

⇒ log ( H+ ) = log 100

We know that - log n = log ( 1/n )

⇒  - ( log 1/H ) = log 100

Take anti log both sides :-

⇒ 1/H = 100

⇒ H = 1/100

⇒Number of moles = hydrogen ion concentration .

Hence, Molarity = 1/100 .

• Molarity (M) indicates the number of moles of solute per liter of solution (moles/Liter) and is one of the most common units used to measure the concentration of a solution.
  • Molarity can be used to calculate the volume of solvent or the amount of solute.
  • The relationship between two solutions with the same amount of moles of solute can be represented by the formula c1V1 = c2V2, where c is concentration and V is volume.
• In chemistry, pH is a scale used to specify the acidity or basicity of an aqueous solution.
  • Acidic solutions are measured to have lower pH values than basic or alkaline solutions.
  • The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution.