Question

Suppose that a small styrofoamtm cooler holds 15.0 l of water heated to 84 ∘
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 33 ∘
c. assume no heat loss to the surroundings.

Answer 1

This can be solve by applying energy balance over the system. The energy gained by the dry ice is equal to the enrgy realesed by the water.

mwCpwdeltaT = mDAHDA

the Cp of water = 4.18 J/gC

enthalpy of sublimation H = 571 J/g

(1000 ml)(1g/ml)(4.18 J/gC)(84 C – 33 C) = mDA(571 j/g)

mDA =373 g dry iceThis can be solve by applying energy balance over the system. The energy gained by the dry ice is equal to the enrgy realesed by the water.

mwCpwdeltaT = mDAHDA

the Cp of water = 4.18 J/gC

enthalpy of sublimation H = 571 J/g

(1000 ml)(1g/ml)(4.18 J/gC)(84 C – 33 C) = mDA(571 j/g)

mDA =373 g dry ice