Question

Dry ice, \({\rm{C}}{{\rm{O}}_{\rm{2}}}{\rm{(s)}}\), does not melt at atmospheric pressure. It sublimes at a temperature of \({\rm{ - 7}}{{\rm{8}}^{\rm{o}}}{\rm{C}}\). What is the lowest pressure at which \({\rm{C}}{{\rm{O}}_{\rm{2}}}{\rm{(s)}}\) will melt to give \({\rm{C}}{{\rm{O}}_{\rm{2}}}{\rm{(l)}}\)? At approximately what temperature will this occur? (See Figure \({\rm{10}}{\rm{.34}}\) for the phase diagram.)

Short answer

At\({\rm{5}}{\rm{.11 atm}}\)the temperature is obtained as:\({\rm{ - 56}}{\rm{.}}{{\rm{6}}^{\rm{^\circ }}}{\rm{C}}\).

Step-by-step solution

Define liquid

One of the states of matter is liquid. Because the particles in a liquid are free to move, while it has a defined volume, it lacks a defined form. Liquids are made up of atoms or molecules joined together by intermolecular connections.

To find the temperature

The minimum pressure at which dry ice will melt to give liquid is at triple point of carbon-dioxide.

The diagram is:

Hence, this is at \({\rm{5}}{\rm{.11 atm}}\) and at \({\rm{ - 56}}{\rm{.}}{{\rm{6}}^{\rm{^\circ }}}{\rm{C}}\)