Dry ice is solid carbon dioxide. instead of melting, solid carbon dioxide sublimes according to the following equation: co2(s)→co2(g). when dry ice is added to warm water, heat from the water causes the dry ice to sublime more quickly. the evaporating carbon dioxide produces a dense fog often used to create special effects. in a simple dry ice fog machine, dry ice is added to warm water in a styrofoam cooler. the dry ice produces fog until it evaporates away, or until the water gets too cold to sublime the dry ice quickly enough. suppose that a small styrofoam cooler holds 15.0 liters of water heated to 90 ∘c. calculate the mass of dry ice that should be added to the water so that the dry ice completely sublimes away when the water reaches 10 ∘c. assume no heat loss to the surroundings.

Explanation:

First of all we need to calculate the heat that the water in the cooler is able to release:

Where:

Cp is the mass heat capacity of waterV is the volume is the density

To calculate the mass of CO2 that sublimes:

Knowing that the enthalpy of sublimation for the CO2 is:

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