Calculating Mass and Volumetric Flow of Nitrobenzene: Homework Solutions

[XBOX999]

Homework Statement

The specific gravity of nitrobenzene is 1.20.
a) Calculate the mass in kg of 250 litres of nitrobenzene.
b) Calculate the volumetric flow in mL/min corresponding to a mass flow of 30 lbm/h of nitrobenzene.
c) Calculate the density of a mixture composed of 20 litres of nitrobenzene and 3 ft^3 of benzene (SG = 0.879), by supposing that the volume of the mixture is the sum of the volume of the two substances.

Homework Equations

SG=p/pref
v=m/p

The Attempt at a Solution

a) I got 1.2*250=300 kg
b) I got v= 183.33 ml/min
C) I do not know how to solve it
I find 3ft^3= 84.950
and I do not how to solve it?Please help me

 

[Tom Creswell]

Mix density = total kg / total liters (or total lbs/ total cu ft). Figure out both totals, then divide.

 

[Blueshift5]

a) Your calculation for the mass of 250 litres of nitrobenzene is correct. Good job!

b) To calculate the volumetric flow, we can use the formula v = m/p, where v is volumetric flow, m is mass flow, and p is density. We can first convert 30 lbm/h to kg/s by multiplying by 0.453592 (1 lbm = 0.453592 kg) and then dividing by 3600 (1 hour = 3600 seconds). This gives us a mass flow of 0.00333 kg/s. Then, using the specific gravity of nitrobenzene, we can calculate the density as 1.2 * 1000 kg/m^3 = 1200 kg/m^3. Plugging these values into the formula, we get v = 0.00333/1200 = 2.78 x 10^-6 m^3/s. To convert this to mL/min, we can multiply by 60000 (1 min = 60 seconds) and then by 1000 (1 m^3 = 1000 L). This gives us a volumetric flow of 0.167 mL/min.

c) To calculate the density of the mixture, we can use the formula SG = p/pref. We know the specific gravity of benzene is 0.879, so we can rearrange the formula to solve for p (density). We get p = SG * pref = 0.879 * 1000 kg/m^3 = 879 kg/m^3. Now, we can use the formula v = m/p to calculate the volume of the mixture. We have 20 L of nitrobenzene, which has a density of 1200 kg/m^3, and 3 ft^3 of benzene, which has a density of 879 kg/m^3. We can convert 3 ft^3 to m^3 by multiplying by 0.0283168 (1 ft^3 = 0.0283168 m^3). This gives us a total volume of 20 L + 0.085 m^3 = 20.085 m^3. Now, we can plug these values into the formula v = m/p to solve for the mass of the mixture. We get m = 20.085 * 1200 + 0.