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OPRA Pharmacokinetics and Pharmacodynamics QUESTION #3843
Question 1
The molecular weight of lithium carbonate ($\text{Li}_2\text{CO}_3$) is $73.89$ with Li atomic weight $= 6.95$. How many millimol of lithium ions are present in a $300$ mg tablet?
  • $2.46$ mmol
  • $4.06$ mmol
  • $8.12$ mmol✔️
  • $12.18$ mmol
Correct Answer Explanation
Moles of $\text{Li}_2\text{CO}_3 = \dfrac{300}{73.89} = 4.06\ \text{mmol}$. Each formula unit contains $2\ \text{Li}^+$ ions, therefore Li $= 4.06 \times 2 = 8.12\ \text{mmol}$.