Find the mass of water (H2O) needed to react with 150 grams of potassium (K)

2K(s) + 2 H2O (g)-2KOH +H2(g)

How do I get the number of moles in H2O?
Desperate to understand this.
I got K= 150g./39.0983=3.84 mols of K.

Then would it be 3.84(2mols H2O/7.68)
How do I get the proper equation to figure out what 2 moles of H2O would be.
If you can walk me through this problem I will understand it and be able to continue with my work.
Is this correct?
3.84 mol(2 H2O/7.68 ????