Calculate the mass of ammonia that contains a trillion hydrogen atoms.

              9.4 × 10⁻¹² g of NH₃

Solution:

Step 1: Calculate Number of NH₃ Molecules containing 1 Trillion Hydrogen Atoms:

As,

                  3 Hydrogen Atoms are present in  =  1 Molecule of NH₃

So,

    1 × 10¹² Hydrogen Atoms will be present in  =  X Molecules of NH₃

Solving for X,

                      X  =  (1 × 10¹² × 1) ÷ 3

                      X =  3.33 × 10¹¹ Molecules of NH₃

Step 2: Calculate Moles of NH₃:

As,

                          Moles  =  Number of Molecules ÷ 6.022 × 10²³

Putting value,

                          Moles  =  3.33 × 10¹¹ Molecules ÷ 6.022 × 10²³

                          Moles  = 5.53 × 10⁻¹³ mol

Step 3: Calculate Mass of NH₃:

As,

                          Moles  =  Mass ÷ M.Mass

Solving for Mass,

                          Mass  =  Moles ×  M.Mass

Putting values,

                          Mass  =  5.53 × 10⁻¹³ mol × 17 g.mol⁻¹

                          Mass =  9.4 × 10⁻¹² g of NH₃

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 !