Coal can be considered to be a binary mixture of non-combustible mineral matter (ash) and combustible organic material (coal). an as-mined coal stream (the feed f) containing 43 wt.% mineral matter (ash) is "beneficiated" (separated) in a dense-medium cyclone to produce a product p containing 8 wt.% mineral matter and a tailings t containing 71 wt.% mineral matter. determine the recovery of the combustibleorganic component (non-mineral matter) from the feed into the product.

be careful - you are not being asked to find the recovery of mineral matter (ash), but the recovery of the combustible component. however, all the concentrations are given in terms of the mineral matter.

give your answer as a percentage (not a fraction) rounded off to one (1) decimal place.

n2(g) + 3h2-> 2nh3(g)   this is the balanced equation

note the mole ratio between n2, h2 and nh3.   it is 1 : 3 : 2   this will be important.

moles n2 present = 28.0 g n2 x 1 mole n2/28 g = 1 mole n2 present

moles h2 present = 25.0 g h2 x 1 mole h2/2 g = 12.5 moles h2 present

based on mole ratio, n2 is limiting in this situation because there is more than enough h2 but not enough n2.

moles nh3 that can be produced = 1 mole n2 x 2 moles nh3/mole n2 = 2 moles nh3 can be produced

grams of nh3 that can be produced = 2 moles nh3 x 17 g/mole = 34 grams of nh3 can be produced

note:   the key to this problem is recognizing that n2 is limiting, and therefore limits how much nh3 can be produced.

the answer is 1260

you spend 7 hours in school for 1 school day with 5 school days in 1 school week with 36 school weeks in a school year.

7*5*36= 1260 it's all about multiplying