Calculate the volume of oxygen required to burn 12.00 l of ethane gas, c2h6, to produce carbon dioxide and water, if the volumes of c2h6 and o2 are measured under the same conditions of temperature and pressure

The  volume of   oxygen required  to  burn  12.00 L  ethane is calculated  as  follows

find the moles  of C2H6  used

At  STP  1 mole  is  always =  22.4 L, what about  12.00 L

= ( 12.00L  x 1 moles)  22.4 L = 0.536  moles

write the   reacting equation

2C2H6+  7O2 = 4CO2  + 6H2O
by  use  of mole  ratio  between  C2H6 :O2   which is 2:7  the  moles  of O2 

= 0.536  x7/2=  1.876  moles

again  at  STP  1mole =  22.4 L  what  about 1.876 moles

=    22.4 L x 1.876  moles/ 1 mole =  42.02 L

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic