text: density problems? if you could help me out with this problem, i'd totally appreciate it. also, could you tell me how to work it out? ok, cool.   "the density of air is 1.3g/l. how many liters of air weigh 2.0 lb?" 1lb = 453.59g so, 2 lb = 907.18g divide this by 1.3g to get the numbe of litres.