Balance the chemical equation?

#("NH"_4)_2 "SO"_4 + "Ca"("OH")_2 -> "CaSO"_4 + "NH"_3 + "H"_2"O"#

1 Answer
Apr 8, 2018

#color(blue)((NH_4)_2SO_4+Ca(OH)_2->CaSO_4+2NH_3+2H_2O)#

Explanation:

A base reacts with an ammonium salt in the following word equation:

#"base + ammonium salt" \ -> \ "salt + ammonia + water"#

We got here the unbalanced equation:

#(NH_4)_2SO_4+Ca(OH)_2->CaSO_4+NH_3+H_2O#

Here, let's balance the nitrogens first. There are two on the left due to the presence of ammonium sulfate, but only one on the right because of one ammonia molecule, so we multiply ammonia by two and get:

#(NH_4)_2SO_4+Ca(OH)_2->CaSO_4+color(blue)2NH_3+H_2O#

Now, I see that there are #4*2+2*1=10# hydrogens on the left, but only #2*3+2=8# on the right side. Six come from two ammonia molecules, meaning that #10-6=4# must come from water molecules. Each water molecule contains two hydrogens, so we multiply water by two to get:

#(NH_4)_2SO_4+Ca(OH)_2->CaSO_4+color(blue)2NH_3+color(red)2H_2O#

Final step is to balance the oxygen. Surprisingly, multiplying #H_2O# by two also balanced out the oxygen molecules, as there are #4+2=6# on the left side, and also #4+2*1=6# on the right side, so this will be the final balanced equation:

#color(blue)(barul(|(NH_4)_2SO_4+Ca(OH)_2->CaSO_4+2NH_3+2H_2O|))#