How many of the following are found in 15.0 mol of benzene (C6H6)? (a) kg C6H6 (b) mol C6H6; (c) Ib-mole C6H6 (d) mol (g-atom) C: (e) mol H: (f) g C; (g) g H: (h) molecules of C6H6.
Answers
12 sigma bonds and 9 pi bonds are present in benzene
Answer:
15.0 kmol = 15, 000 mol
molecular weight benzene = 78 g/mol
molecular weight 6C = 72 g/mol
molecular weight 6 H = 6 g/mol
a) (78 g/mol)( 15, 000 mol )(1 kg/ 1000 g) = 1,170kg
b) 15.0 kmol (1000 mol/ 1 kmol) = 15, 000 mol C6H6 or 1.50x 10^4 mol C6H6
c) A lb-mol is number of units in 12 lb of Carbon twelve isotope,as compared to the g-mol of 12 g of Carbon twelve
The conversion is 1 lb-mol/ 453.592 g-mol
Where do they get the conversion?
The conversion factor is (1 lb-mol/453.592 mol ) ( 1 kg/ 2.2 lb)(1000 g/ 1 kg) = 1.00 g-mol
After all, a mol is the unit representing 12 g of Carbontwelve.
Starting with 12 lb of Carbon twelve,
(12 lb C)(1 kg/2.2 lb) (1000 g/ 1 kg)( 1 mol/ 12 g C)= 454 g-molin a lb-mol. The lb-mol is a misnomer. It is not pounds multipliedby moles, but it is moles as derived from pounds.
(15,000 mol C6H6) ( 1 lb-mol/ 453.592 mol) = 33.1 lb-molC6H6
d) A g-mol
For Carbon alone,
(15,000 mol C6H6) ( 6 mol C/ 1 mol C6H6)= 90, 000 g-mol C or9.00 x 10^4 mol C
e) mol H
(15, 000 mol C6H6) ( 6 mol H/ 1 mol C6H6) = 90, 000 mol H or9.00 x 10^4 mol H
f) g C
(90, 000 mol C )(12 g / mol C) = 1.08 x 10^6 gC
g) g H
(90, 000 mol H) (1 g/mol H) = 90,000 g H or 9.00 x 10^4 gH
Adding f) and g) gives you the equivalent of a), so you can checkyour answer here.
h)
Whenever you see the word "molecules" use Avogadro's number 6.023 x10^23 molecules/mol
(15, 000 mol C6H6)( 6.023 x 10^23 molecules/mol) = 9.03 x10^27 molecules
Overall my answers seemed to agree with the answerslisted above, except for part d. Hopefully, my explanation makes sense to you.