Write a balanced molecular equation describing each of the following chemical reactions:
(a)solid calcium carbonate is heated and decomposes to sold calcium oxide and carbon dioxide
(b)gaseous butane, c4h10, reacts with diatomic oxygen gas to yield gaseous carbon dioxide and water vapor
(c)aaqeous solutions of magnesium chloride and sodium hydroxide react to produce solid magnesium hydroxide and aqueous sodium chloride
(d)water vapor reacts with sodium metal to produce solid sodium hydroxide and hydrogen gas

Explanation:

a)

1 mol of solid calcium carbonate on heating gives 1 mol of calcium oxide and 1 mol of carbon dioxide gas.

b)

2 moles of butane gas when reacts with 13 moles of diatomic oxygen gas to give 8 moles of carbon dioxide gas and 10 moles of water vapors.

c)

1 mol of magnesium Cordelia  reacts with 2 moles of sodium hydroxide to give 2 moles of aqueous sodium chloride solution and 1 mol of solid magnesium hydroxide.

d)

2 mole sof water vapors reacts with 2 moles of sodium metal to give 2 moles of solid sodium hydroxide and 1 mol of hydrogen gas.

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g