Question

A student used a pipette to add 25.0 cm of KOH of unknown concentration to

a conical flask.
The student carried out a titration experiment to find the volume of 0.150 mol/dmº
H2SO4 needed to neutralise the KOH.
The student found that, on average, 17.20 cm of the H2SO4 solution was
required for neutralisation.


Calculate the concentration of the KOH solution.
​

Answer 1

The concentration of the KOH solution = 0.2064 M

Further explanation

Titration is a procedure for determining the concentration of a solution (analyte) by reacting with another solution whose known concentration (usually a standard solution) is called the titrant. Determination of the endpoint/equivalence point of the reaction can use indicators according to the appropriate pH range

Acid-base titration formula

Ma Va. na = Mb. Vb. nb

Ma, Mb = acid base concentration

Va, Vb = acid base volume

na, nb = acid base valence (number of ions H+/OH-)

a=H₂SO4(valence = 2, H₂SO4⇒2H⁺+SO₄²⁻, 2 ions H⁺)

b=KOH(valence = 1, KOH⇒K⁺+OH⁻, 1 ion OH⁻)

Ma = 0.15 M

Va = 17.2 cm³

Vb=25 cm³

The concentration of the KOH(Mb) :

`\tt 0.15* 17.2* 2=Mb* 25* 1\\\\Mb=0.2064`