Octane (C8H18) Molar Mass (With Calculations)

Octane (C8H18) Molar Mass

Molar mass of Octane (C8H18) is 114.232 g/mol.

Well, now you have come to know the molar mass of Octane.

But how can you get this value?

Let me show you the calculation to get the molar mass of Octane (C8H18).

If you are a visual learner like me, then here is a short one minute video for you.

Octane (C8H18) Molar Mass Calculation

If you have a periodic table with you, then you can easily calculate the molar mass of Octane (C8H18).

Because the molar mass of any molecule (or compound) can be calculated by simply adding the molar masses of individual atoms.

Now here we have to find the molar mass of Octane (C8H18).

So for that, have a look at the periodic table given below.

You can see the molar mass value of all the atoms from this periodic table.

Now in Octane (C8H18), there are 8 Carbon atoms and 18 Hydrogen atoms.

So let’s look at the molar mass of Carbon and Hydrogen from the above periodic table.

You can see that;

The molar mass of Carbon is 12.011 g/mol. [1]

The molar mass of Hydrogen is 1.008 g/mol. [2]

Now, to calculate the molar mass of Octane, you just have to add the molar mass of all the individual atoms that are present in Octane.

You can see that in Octane, there are 8 Carbon atoms and 18 Hydrogen atoms.

So, Molar mass of Octane (C8H18) = Molar mass of 8 Carbon (C) atoms + Molar mass of 18 Hydrogen (H) atoms.
= (12.011) 8 + (1.008) 18
= 96.088 + 18.144
= 114.232 g/mol

Hence the Molar mass of Octane is 114.232 g/mol.

I hope you have understood the short and simple calculation for finding the molar mass of Octane.


  • In some books, you may see the unit of molar mass as grams/mole or g/mole. But all these units (i.e g/mol, grams/mole and g/mole) are the same. 
  • Always follow the calculation order to avoid any mistakes in calculation. First solve the brackets, then multiplications and at last do the final addition.
  • And don’t forget to put the unit g/mol to your final calculated molar mass.

Check out other related topics for more practice;
Ammonium sulfate Molar Mass
Calcium hydride Molar Mass
CaSO4 (Calcium sulfate) Molar Mass
Ammonium phosphate Molar Mass
Sulfur hexafluoride (SF6) Molar Mass


Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. With a desire to make learning accessible for everyone, he founded Knords Learning, an online learning platform that provides students with easily understandable explanations.

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