please can i actually receive some help please

Question

S   +   6 HNO₃  -->  H₂SO₄  +  6 NO₂  +   2 H₂O

In the above equation how many moles of water can be made when 47 moles of HNO₃ are consumed?

Please give and only give explanation and solution.

Answer 1

Hello, Jackie,

The answer is easier than you think, since you've already provided the balanced equation for the reaction.

S   +   6 HNO₃  -->  H₂SO₄  +  6 NO₂  +   2 H₂O

We can read a balanced equation as either individual atoms/molecules (1 atom of sulfur rectacts with 6 molecules of nitric acid to yield 1 molecule of sulfuric acid, 6 molecules of NO₂, and 2 molecules of water), or as moles (1 mole of sulfur reacts with 6 moles of nitric acid, etc.).

The approach to finding the answer you want involves the molar ratio of the two substances in question, HNO₃ and H₂O. The equation says we get 2 H₂O when we start with 6HNO₃. We can say:

(2 moles H₂O)/(6 moles HNO₃)

Note: [We can also invert this conversion factor:

(6 moles HNO₃)/(2 moles H₂O)]

If we start with 47 moles of HNO₃ then the amount of water produced is:

(47 moles HNO₃)*(2 moles H₂O)/(6 moles HNO₃) = (94/6) moles H₂O

Or 15.7 moles of water.

If you had asked how many molecules of water are produced with 47 molecules of nitric acid, it would be 15 molecules of water, rounded to the nearest intact molecule.

Bob

Answer 2

So Jackie R.,

Actually, you can easily solve.

Starting with your #moles HNO₃ , multiply by a ratio, namely (#moles H₂O in equation)/(#moles HNO₃ in equation). The result is the (quantitative) conversion of the HNO₃ into H₂O. Balanced equations look like just a certain # of molecules of reactants reacting, but they can just as well represent a certain # of moles of reactants reacting.

So -- Start with moles, end with moles! (same rules apply in my front yard, unfortunately -- but that's a different kind of moles)

-- Cheers, --Mr. d.