Rock the Pharmacy PEBC Test 2025 – Your Prescription for Success!

To determine how many milligrams of zinc sulfate heptahydrate would provide the same amount of elemental zinc as 220 mg of anhydrous zinc sulfate, it's essential to first calculate the amount of elemental zinc present in the 220 mg of the anhydrous form.

Anhydrous zinc sulfate has a molecular weight of 161 g/mol. Of this, zinc (which has a molecular weight of 65 g/mol) represents approximately 40.37% of the molecular weight of the anhydrous form. This means that for every 161 mg of anhydrous zinc sulfate, 65 mg is elemental zinc.

To find the elemental zinc in 220 mg of anhydrous zinc sulfate:

1. Calculate the zinc content:

\[

\text{Elemental zinc} = \left( \frac{65 \, \text{mg}}{161 \, \text{mg}} \right) \times 220 \, \text{mg} = 86.83 \, \text{mg}

\]

Now, we need to find out how much zinc sulfate heptahydrate is needed to obtain the same amount of elemental zinc. Zinc sulfate heptahydrate (Zn