Calculating the Decomposition of CaCO3 Calcium carbonate (CaCO3), an important component of coral reefs, can decompose when heated, forming calcium oxide (CaO) and carbon dioxide (CO2) according to the equation below: CaCO3 es002-1. Jpg CaO CO2 How many moles of CaO form when 98. 60 g CaCO3 decompose? 98. 60 g CaCO3 = 0. 9851 mol CaO To determine the mass of CO2 that forms from a given mass of CaCO3, which of the following must be known? Check all that apply. Molar mass of CaCO3 molar mass of CaO mole ratio of CaCO3 to CO2 mole ratio of CaO to CO2 molar mass of CO2 mass of CaO formed.

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.

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