Answer to Question #299590 in General Chemistry for kml

Question

The concentrated sulfuric acid we use in the laboratory is 98.0 percent H₂SO₄ by mass. Calculate the molality and molarity of the acid solution. The density of the solution is 1.83g/mL

Answer 1

1 L = 1000 mL of solution

Mass of solution = volume x density

$Mass of solution = 1000\times1.83 = 1830 g=1000×1.83=1830g$

Mass of $H_2SO_4 =\frac{ 98.0}{100} × 1830 = 1793.4 g$

$Moles of H2SO4 = \frac{mass}{molar mass of H2SO4}$

$\frac{ 1793.4}{98.08} = 18.3 moles$

$Molarity =\frac{ moles of H2SO4}{volume of solution in L}$ Molarity = moles of H2SO4/volume of solution in L

$\frac{18.3}{1} = 18.3 M$

Mass of water $= 1830 - 1793.4 = 36.6 g = 0.0366 kg$

$Molality = \frac{moles of H2SO4}{mass of water in kg}$

$\frac{18.3}{0.0366} = 500 mol/kg = 500M$