# The molecular formula of lithium carbonate is Li2CO3. What is the molecular weight of this drug?

Its formula mass is $73.89$ $g \cdot m o {l}^{-} 1$.
As you know this salt is commonly used to treat mania. The formula mass is simply the sum of the molar masses of the contributing atoms: i.e. $\left(2 \times 6.94 + 12.011 + 3 \times 15.999\right) \cdot g \cdot m o {l}^{-} 1$ $=$ ??