A 200 g sample of water at 60.0 degrees Celsius is heated to water vapor at 140.0 degrees Celsius. Expected Answer = 501,440 J Before trying to solve this problem, explain: what is happening to the water from 60.0 degrees Celsius to 100.0 degrees Celsius?
what happens at 100.0 degrees Celsius?
what happens from 100.0 degrees Celsius to 140.0 degrees Celsius?
Then solve the full problem, showing work & units.

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 !