Two aqueous sulfuric acid solutions containing 20.0 wt% H2SO4 (SG=1.139) and 60.
ID: 701066 • Letter: T
Question
Two aqueous sulfuric acid solutions containing 20.0 wt% H2SO4 (SG=1.139) and 60.0 wt% H2SO4 (SG=1.498) are mixed to form a 4.00 molar solution (SG=1.213)
Taking 100 kg of the 20% feed solution as a basis, draw and label a flowchart of this process, labeling both masses and volumes, and do degree of freedom analyisis. Calculate the feed ratio (liters 20% solution/liter 60% solution.
In addition to (a)-(c), using the 100 kg basis described in part (b) calculate the volume of the resulting mixture (V3) and compare it to the sum of the two feed volumes – was volume conserved?
Explanation / Answer
100 kg/(1,139 kg/m3 ) = 0.0878 m3 = 87.8 L
Sulfuric acid balance: 100 (0.2) + m2 (0.6) = m3 (0.323)
20 + 0.6 m2 = 0.323 m3
m2 = 0.538 m3 - 33.33
Water balance: 100 (0.8) + m2 (0.4) = m3 (10.323)
80 + 0.4 m2 = 0.677 m3 80 + 0.4 (0.538 m3 - 33.33) = 0.677 m3
80 + 0.2152 m3 - 13.33 = 0.677 m3 66.67 = 0.4618 m3
m3 = 144 kg
V3 = 144 kg/(1,213) kg/m3 = 118.7 m3
m2 = 0.538 (144) - 33.33 = 44.14 kg
V2 = 44 kg/(1,498 kg/m3 ) = 0.0294
m3 = 29.37 L
Feed ratio = 87.8 L (20% solution)/29.37 L (60% solution) = 2.99 L of 20% solution/L of 60% solution