Question

A is an aqueous solution of H2SO4 of concentration 0.05 moldm3,B is put A intoa burette pipette 25cm3 of B into a conical flask and add two drops of methyl orange indicator

What is the concentration in moldm3 of NaOH in B given the equation for reaction H2SO4+2NaOH

What is the percentage purity of the NaOH

What is the percentage of the impurity present

Answer 1

Since the volume of H₂SO₄ is not given, let's assume it was 20.0cm³.

Moles of H₂SO₄ = 0.05×20÷1000= 0.001

Moles of NaOH= 0.001×2= 0.002

Concentration of NaOH= (0.002÷25)×1000= 0.08M

Percentage purity of NaOH

Mass of NaOH in 1dm³= 0.08×40= 3.2g

Assuming density of solution is 1g/cm³,

Percentage purity=( 3.2÷1000)×100

=0.32%

Percentage impurity= 100-0.32

= 99.68%