The CO2 exhaled by astronauts must be removed from the spacecraft atmosphere. One way to do this is with solid LiOH:
CO2(g) + 2 LiOH(s) Li2CO3(s) + H2O(l)
The CO2 output of an astronaut is about 1.2 kg/day. What is the minimum mass of LiOH required for a six-day space shuttle flight involving five astronauts?