chemistry
posted by Corryn on .
One essential step in the manufacture of many plant fertilizers is the production of nitrogen monoxide gas. NO(g). This step is represented by the following balanced equation.
4 NH3(g) + 5 O2(g)= 4 NO(g)+ 6 H2O(l)
Determine the amount of oxygen needed to produce 1.2 x 10^4 mol of nitrogen monoxide gas.

1.2E4 mol NO x (5 moles O2/4 moles NO) = moles O2 needed.

if that's the straight up answer can someone please explain it to me...im so lost.

Straight up, straight down, straight laterally, here's the scoop.
When you have moles of anything and an equation, all you really need to do is to convert from moles of one entity to moles of another. The way you do that is to use the coefficients in the balanced equation as I have done in the answer I provided. Note the following and how the units cancel.
moles O2 = moles NO x (5 moles O2/4 moles NO).
moles O2 = 1.2E4 moles NO x (5 moles O2/4 moles NO).
Note that moles NO (from 1.2E4 molesNO) in the numerator cancel with moles NO in the denominator of the second part (from the 4 moles NO) but nothing cancels with the moles O2 in the numerator. Therefore, you have converted moles NO to moles O2 simply by multiplying 1.2E4 x (5/4) = ??
You may convert moles NO to moles of anything else in the equation the same way. Actually, this gives you a way of converting any moles in any equation to other moles of reactants or products in the same equation. If you get the hang of this you can work just about any chemistry problem there is that deals with stoichiometry.