Adding delta G values when Using Hess's Law

[Hanna Masri 3C]

When using Hess's law, do you add the delta g values of all the separate equations or do you multiply them. Also when using hess's law, how do you manipulate the delta g values in relation to how you manipulate the equation (if you multiply the equation what do you do to the delta g values)?

[Sahana Ravishankar]

Hi! When there are multiple steps and separate equations in a reaction, you would have to add the different delta g values to find the total. As for the part about the effects of manipulating the equation, if the equation is multiplied by a coefficient, then the delta g for that equation is also multiplied by the same coefficient. If the equation is reversed, then the sign of the delta g value is also reversed (since in the reverse direction, the reaction would change from endothermic to exothermic and vice versa). Hope this helps!

[Tiffany Wang 2G]

I think you mean delta H, but yes, you add them together with Hess's law. When you reverse the reaction, you would get the negative delta H and then add it together. If you multiply the reaction by a constant, you would multiply the delta H of that reaction and add it to the total.