hess's law

[Kaylee Clarke 1G]

when using hess's law and cancelling out the data, does it matter if a molecule is on the product or reactant side to cancel with another? I know that they must have the same moles to cancel, but do they have to be on opposite sides of the reaction equation?

[Aarja Pavade 1H]

Yes, to cancel out they must be on opposite sides of a reaction. A product forms while a reactant is used up. If H2 is formed in one reaction (product) and is then used as a reactant (with the equivalent amount of moles) in another reaction, it will cancel out. Using this same rationale, if they were on the same side they would be added.

[Anna Heckler 2C]

A molecule can only be canceled if it occurs in the same number of moles on the reactant and product side. This means they are balanced and can cancel.

[Betania Hernandez 2E]

Yes, they must be on the opposite sides of the reaction equation in order to cancel out.

[Ryan Yoon 1L]

It does matter for the molecules to have the same amount on the product and reactant side as they are intermediates in the reaction that get canceled.

[Leyna Dang 2H]

Yes, they need to be on opposite sides to cancel out. When the equal number of moles of the reactant and product you're looking at are on opposite sides, they balance out and therefore cancel.

[Junwei Sun 4I]

Yes they need to be on opposite side to be cancelled out.

[ThomasNguyen_Dis1H]

Yes they need to be on opposite sides to cancel out with one another. It usually works out since most of the times it's obvious what product and reactant you want.

[Lizette Noriega 1H]

Yes, they must be on opposite sides and they have to be balanced in order to cancel them out

[Madeline Phan 1E]

Yes, they need to be on opposite sides of the reaction to cancel out.

[AniP_2D]

In order to cancel out, the molecules must be on opposite sides. This may require you to reverse a reaction and change the enthalpy of the reaction in order to make canceling them out possible.

[Celine 1F]

Molecules can only be cancelled if they are on opposite sides of the equation

[Veronica Lu 2H]

if they have the same number of moles on both sides they cancel out

[John Liang 2I]

indeed, you must cancel out only if the same compound is on both sides of the equation.