How many moles are in a sample of Sodium that contains 1.806 x 1024 atoms?

3 moles Na

Explanation: To find the number of moles of Na, divide the number of atoms of Na with the Avogadro's Number.

1.806x10²⁴ atoms Na x 1 mole Na / 6.022x10²³ atoms Na

= 2.99 or 3 moles Na

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 !