The Molarity of Concentrated of H2SO4 (Sulfuric Acid)
Molarity of concentrated of sulfuric acid (H2SO4) can be calculate if the density of the solution and its percentage concentration are known. We usualy calculate the molarity of concentrated sulfuric acid when we will preapare the more dilute of H2SO4 solution. We do this more in the analytical experiments. But the easy way is to take a look on the label of the container of the concentrated sulfuric acid solution. From this we can get the density and the percent by mass of this solution. How we can calculate the molarity of concentrated H2SO4? just take the example below:
“Calculate the molarity of concentrated of H2SO4 (sulfuric acid solution) that has the spesific gravity 1.84?”
Here the answer:
First we should now the definition of specific gravity (SG). SG is defined as the ratio of density of the material to the density of water at a specified temperature 4oC. Specific Gravity is dimensionless and can be expressed as
SG = p / pH2O
where
p = density of the material
p = density of H2O at 4oC= 1000 Kg/m3 = 1 g/cm3
from the formula above we can calculate the density of the concentrated of sulfuric acid solution as
density of concentrated H2SO4 solution
= SG x pH2O
= 1.84 x 1 g/cm3
= 1.84 g/cm3
= 1.84 g/mL
Assume that we have 100 mL of the concentrated of sulfuric acid thus we can calculate the mass of this solution
mass of solution
= volume x density
= 100 mL x 1.84 g/mL
= 184 g
mass of H2SO4 in this solution can be calculate by multipliying the mass of the solution with its concentration
mass H2SO4
= mass of the solution x percentage
= 184 g x 98%
= 180.32 g
and the moles of H2SO4 are
= mass / molar mass
= 180.32 g / 98.086
= 1.838 mol
and finaly the concentration of concentrated H2SO4 solution can be calculate by dividing the moles with the volume of the solution
Molarity H2SO4 concentrated = 1.838 mol / 0.1 L
Molarity H2SO4 concentrated = 18.38 M
Add comment June 12th, 2008