Question

The number of millimoles of H2SO4 present in 5 litres of 0.2N H2SO4 solution is

1. 1.500 2. 1000 3. 250 4. 0.5 x 10 -3

Answer 1

There are 1000 milimoles in 1 mole and 1milimole = 0.001 mole

We can use this information to calculate the number of milimoles in this solution of sulphuric acid.

Calculate the number of moles of 5 liters of 0.2N H₂SO₄:

Step 1: Convert the 0.2N( Normality) to Morlarity

- Normality is converted to Morlarity by dividing the Noramilty by the number of hydrogen ions in the acid ( or hydroxide ions in the base)

- Hydrogen ions in H₂SO₄ are 2

             ∴ Molarity of 0.2N H₂SO₄  =  0.2/2 = 0.1 Molarity

Step 2: Calculate the number of moles of 0.1M H₂SO₄

            Molarity  =  moles of solute / liter of solution

             Moles = molarity × liter of solution

             ∴ Moles of 5 liters of 0.1M H₂SO₄ = 0.1M × 5liters

                                                                   =  0.5 moles

Therefore the moles of 0.2N H₂SO₄ = 0.5 moles

Convert 0.5 moles to milimoles: 

1 mole = 1000milimoles

0.5 moles = 1000milimoles × 0.5 moles/1 mole

                 = 500 milimoles

Therefore the number of milimoles present in 0.2N H₂SO₄ are 500 milimoles(choice 1)

Answer 2

Good question !

Answer