What do the coefficients/subscripts represent [ENDORSED]

[sylvie_1D]

Hi, so I was solving problem E29, and I was curious as to how many moles of hydrogen are there in 4H2O? Someone has told me 8 and another has told me 2.

[Jennifer Ma 1G]

In a single H20 molecule, there are 2 atoms of hydrogen. However, the coefficient 4 in front of the H20 means there are 4 H20 molecules. So, there are 8 total atoms of hydrogen in the 4H20 molecules (2 atoms of hydrogen per 1 H20 molecule x 4 H20 molecules = 8 atoms of hydrogen atoms).

[Haison Nguyen 1I]

When there is a coefficient in front of a molecule, you would multiply that number by the number of atoms in each element. So for H20, there are 2 hydrogen atoms and one oxygen atom. However, since there is a coefficient of 4 in front of it, you would multiply it by each element and get 8 hydrogen atoms and 4 oxygen atoms.

[Christina Inchuachan 1C]

Coefficients represent the number of molecules in the equation while the subscripts represent the number of atoms of the element.

[Shione Nakahara 1F]

4 molecules of H20 has 8 atoms of hydrogen total

[Nimrat Brar 1E]

Coefficients represent the amount of molecules that are part of the equation so in your example, since there are 4 molecules of H20, there would be a total of 8 hydrogen atoms.

[Reese - Dis 1G]

The coefficient is called the stoichiometric coefficient and it is what you can change to balance equations, but it also tells you how many moles of a molecule you have. In this example, 4 is the stoichiometric coefficient, so you would have 4 moles.

[Chem_Mod]

Most of the above answers are correct. There should be 8 moles of hydrogen because there are 4 molecules with 2 hydrogen atoms each. If we were referring to the number of moles of water, then the answer would be 4 (4 molecules of water total).