The gas-phase decomposition of ch3cho (g) occurs according to the equation
ch3cho (g) > ch4 (g) +co (g) and is second order. the value of the rate constant is 0.105 m-1 x s-1 at 490 degrees celcius. if the concentration of ch3cho (g) is 0.012 m initially, what will be its concentration 5.0 minutes later.

Concentration of CH3CHO  5.0 minutes later is

M or 0.00871 M

Explanation:

The concentration for second order reaction can be calculated using the formula:

Here , [A] = Concentration of substance at time t

t = time

= Initial concentration

k = rate constant

According to question :

[A]  = Concentration of CH3CHO at time 5.0s = ?

= 0.012 M

t = 5.0 min

Convert it into second (because rate constant units are in second)

1 min = 60 s

t = 5 x 60 = 300 s

k = 0.105 M-1 s-1

Insert these value into,

M

Hence ,concentration of CH3CHO  5.0 minutes later is

M or 0.00871 M

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 

Hbr dissociates to form h+ and br-ca(oh)2 dissociates to form ca2+ and 2oh-the h+ and oh- react to form waterassuming the reactants are dissolved in water, the net reaction is h+ + oh- —> h2oif you’re asked to show all components of the reaction, the complete reaction is 2hbr + ca(oh)2 —> cabr2 + 2h2o