Calcula la cantidad de estaño contenida en 200g de bronce si su riqueza es de 18%.

The amount present is 36g

Explanation:

Here, we are interested in calculating the amount of zinc in the bronze alloy since it is 18% of the total mass

What we do here is to calculate 18% of the total 200g

Mathematically, that would be 18/100 * 200 = 18 * 2 = 36g

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 !