Hydroxide (OH-) ion Molar Mass (With Calculations)

Molar mass of Hydroxide (OH-) ion is 17.007 g/mol.

Well, now you have come to know the molar mass of OH- ion.

But how can you get this value?

Let me show you the calculation to get the molar mass of OH- ion (Hydroxide ion).

You can also refer to this one minute video which will show you the simple steps to calculate the molar mass of any compounds.

Hydroxide (OH-) ion Molar Mass Calculation

If you have a periodic table with you, then you can easily calculate the molar mass of OH- ion (Hydroxide ion).

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 OH- ion (Hydroxide ion).

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 OH- ion, there is 1 Oxygen atom and 1 Hydrogen atom.

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

You can see that;

The molar mass of Oxygen is 15.999 g/mol. ^[1]

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

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

You can see that in OH- ion, there is 1 Oxygen atom and 1 Hydrogen atom.

So, Molar mass of OH- ion = Molar mass of 1 Oxygen (O) atom + Molar mass of 1 Hydrogen (H) atom.
= 15.999 + 1.008
= 17.007 g/mol

Hence the Molar mass of OH- ion is 17.007 g/mol.

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

Remember

• 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;
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Dichloromethane (CH2Cl2) Molar Mass
MgF2 (Magnesium fluoride) Molar Mass