Question

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 22 ∘

c. assume no heat loss to the surroundings.

Answer 1

15 liters H2O = 15*1000g = 15,000 grams
heat needed to raise one gram water, one degree celsius = 4.18J

4.18J * 15,000g = 62,700J = 62.7kJ needed per degree C

85 - 22 = 63C temp drop needed

62.7 kJ * 63C = 3950.1kJ needed from CO2

enthalpy of CO2 = 393.51kJ/mol
CO2 = 44g/mol = 22.73 moles/kg
393.51kJ/mol * 22.73 moles/kg
= 8,943.4 kJ/kg

3950.1kJ / 8,943.4 kJ/kg = .4417 kg of CO2 needed