What is the molar mass of Disodium sulfide nonahydrate (Compound)
I'm confused about the number of moles per element

240 g/mol

Explanation:

We'll begin by writing the chemical formula of Disodium sulfide nonahydrate. This is illustrated below:

The molecular formula of disodium sulfide nonahydrate is Na₂S.9H₂O

Finally, we shall determine the molar mass of disodium sulfide nonahydrate, Na₂S.9H₂O. This can be obtained by adding the individual molar mass of the element present in the compound as illustrated below:

Molar mass of Na₂S.9H₂O = (23×2) + 32 + 9[(2×1) + 16]

= 46 + 32 + 9[2 + 16]

= 46 + 32 + 9[18]

= 46 + 32 + 162

= 240 g/mol

Thus, the molar mass of disodium sulfide nonahydrate, Na₂S.9H₂O is 240 g/mol