General Chemistry Challenge Problem: Gases
Cyanogen, a highly toxic gas is 46.2% C and 53.8% N by mass. At 25 degrees Celsius and 751 torr, 1.05g of cyanogen occupies 0.500 L.
A) What is the molecular formula of cyanogen.
B) Predict the molecular structure
C) Predict its polarity.

Question

General Chemistry Challenge Problem: Gases
Cyanogen, a highly toxic gas is 46.2% C and 53.8% N by mass. At 25 degrees Celsius and 751 torr, 1.05g of cyanogen occupies 0.500 L.
A) What is the molecular formula of cyanogen.
B) Predict the molecular structure 
C) Predict its polarity.

anonymous · Answer

Have the answers. Lets see who knows all 3.

anonymous · Answer

Medal and fan.

aaronq · Answer

a) Formula for $\sf C_xN_y$

$\sf PV=nRT=\dfrac{mRT}{M}$

$\sf M_{C_xN_y}=\dfrac{mRT}{PV}=\dfrac{1.05~g*(62.36367~L~torr~K^{-1}mol^{-1})*298.15~K }{751~torr*0.5~L}=51.99~g/mol $

$\sf M_{C_xN_y}\approx  52~g/mol=x~12~g/mol+y~14~g/mol$

Trial and error gives $\sf C_2N_2$ 

The structure is probably |dw:1439562426305:dw|

The structure does not have a permanent dipole moment because of symmetry - individual dipole moments caused by the lone pairs on the N terminal atoms cancel each other out.

aaronq · Answer

|dw:1439563030483:dw|

anonymous · Answer

Wow, nice.
All 3 steps correct.