Chemical Equations?

[josephyim1L]

I don't quite understand what the coefficients in a chemical equation represent. Today in class, Professor Lavelle mentioned that the coefficients represent moles, and that the # of moles aren't the same, but the number of atoms are...

Don't the coefficients for each element or molecule just represent the number of atoms? For example, 2 H_2 is just 2 molecules of hydrogen gas? Or is it 2 moles of hydrogen gas?

[Gary Qiao 1D]

The coefficients in a chemical equation are pretty much the stoichiometric coefficients, which means that the coefficients really represent the ratio between the substances in a reaction, so it is not necessarily always the exact molar amount. Expanding to your hydrogen gas example, for the equation
2 H2 + O2 --> 2 H2O, the coefficients show that the ratio between hydrogen, oxygen, and water in the reaction is 2 to 1 to 2.

[Parth Mungra]

It can be viewed as either. Breaking it down by viewing it as atoms can make it simple to understand the reaction, but looking as the coefficients as moles makes mass percent composition easier to understand because the amu of each element is in grams per mole.

[Jessica Castro 2H]

The coefficients in a chemical equation represent the ratio of moles required among molecule for the reaction to occur. They do not represent the actual number of moles. Also, remember that moles are a representation of a number (i.e. a dozen = 12, whereas 1 mole = 6.022 x 10^23).

[Saachi_Kotia_4E]

The coefficient is showing the ratio of each molecule in a chemical equation. It's easier to understand if you think of it like the number of atoms or molecules in an equation, but if you are doing any calculations, it would be considered the number of moles. It technically is the number of moles for that reaction to occur in writing, but it is easier to understand as the number of atoms/molecules, and it really only shows the ratio of each molecule.