# I need help with part b I already know how to do part a.   Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the 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 L of water heated to 86 °C. The specific heat of water is 4.184 J/g·°C.   a) Use standard enthalpies of formation to calculate the change in enthalpy for dry ice sublimation. (The ΔHºf for CO2(s) is -427.4 kJ/mol, and for CO2(g) is –393.5 kJ/mol)   Answer: 33.9 kj   b) 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 13 °C. Assume no heat loss to the surroundings.

Question

I need help with part b I already know how to do part a.

Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the 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 L of water heated to 86 °C. The specific heat of water is 4.184 J/g·°C.

a) Use standard enthalpies of formation to calculate the change in enthalpy for dry ice sublimation. (The ΔHºf for CO2(s) is -427.4 kJ/mol, and for CO2(g) is –393.5 kJ/mol)

b) 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 13 °C. Assume no heat loss to the surroundings.