### What do the coefficients/subscripts represent

Posted:

**Sun Apr 08, 2018 9:29 pm**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.

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=26&t=30525

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Posted: **Sun Apr 08, 2018 9:29 pm**

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.

Posted: **Sun Apr 08, 2018 9:56 pm**

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).

Posted: **Mon Apr 09, 2018 11:34 am**

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.

Posted: **Sun Apr 15, 2018 9:11 pm**

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

Posted: **Sun Apr 15, 2018 9:19 pm**

4 molecules of H20 has 8 atoms of hydrogen total

Posted: **Sun Apr 15, 2018 9:38 pm**

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.

Posted: **Mon Oct 01, 2018 2:58 pm**

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.

Posted: **Mon Oct 01, 2018 3:20 pm**

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).