Question

1-What is a mol of a species of molecular weight , in terms of (a) a number of molecules? (b) a mass?

2-What is a ton-mole of a species?

3-How many lb-moles and lb of (a) H and (b) H are contained in 1 lb-mole of H O?

4-How many gram-moles of C H are contained in 2 kmol of this substance?

5-One hundred kilograms of molecular hydrogen (H ) is fed into a reactor each hour. What is the molar flow rate of this stream in gram-moles/hour?

Answer 1

1. moles of species :

The number of molecules in a mole known as Avogadro's constant, N_A : 6.022 *10²³ mole-1

In molecular weight terms , grams equal to the substance's molecular weight in atomic mass units, or amu is a mole : mass of mole is known as molar mass.

   in terms of (a) a number of molecules :

    no. of moles , n = No. of molecules / N_A    or   No. of molecules / 6.022 *10²³ mole-1

(b) a mass :   mass in grams / molecular weight

2.

One ton is 2,000 pounds, and 1,000 grams = 2.2 pounds.

So one ton is:

2000 * (1000/2.2) = 909,091 grams

ton mole : mass in ton / /molecular weight

3.

How many lb-moles and lb of (a) H and (b) H are contained in 1 lb-mole of H O?

lb mol = [mass in lb]/molecular weight

1 lb-mole of H O : lb-moles of H = 1

1 lb-mole of H O : 17 lb

It contains 1 lb H.

4. How many gram-moles of C H are contained in 2 kmol of this substance?

kmol = kgmol

1 kg mol = 1000 gram-moles

thus in 2 kmol of CH = 2000 gram-moles of C H

5-

One hundred kilograms of molecular hydrogen (H ) is fed into a reactor each hour. What is the molar flow rate of this stream in gram-moles/hour?

100 Kg molecular hydrogen H₂ : 100*1000 gram H₂ = 100000 gram H₂

2 gram H₂ = 1 gram-mol H₂

molar flow rate of this stream in gram-moles/hour : 50,000 gram-moles/Hour