Given the following reaction, how many liters of H2 gas are needed to form 35.5 grams of NH3? N2 + 3H2 -> 2NH3

170.4L

Explanation:

The reaction equation is given as:

        N₂  +   3H₂  →    2NH₃  

Mass of NH₃    =  35.5g

Problem:

How many liters of H₂ are needed to produce 35.5g of NH₃  

Solution:

To solve this problem, let us find the number of moles of NH₃;

           Number of moles  =

Molar mass of NH₃   = 14 + 3(1)  = 17g/mol

 So;

            Number of moles  =  = 5.07mole

From the balanced reaction equation:

               2 mole of NH₃   will be produced from 3 mole of H₂  

               5.07mole of NH₃ will produce     = 7.61mole of H₂

At STP;

       1 mole of gas will occupy 22.4L

     7.61 mole of H₂ will occupy 7.61 x 22.4  = 170.4L

h let me think

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !