Pharmacy PEBC Practice Exam

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Prepare for the Pharmacy PEBC Exam with comprehensive quizzes and detailed explanations. Utilize multiple choice questions and flashcards to enhance your understanding and readiness for the exam!

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A patient is currently taking 220 mg of anhydrous zinc sulphate. To receive the equivalent amount of elemental zinc, how many milligrams of zinc sulphate heptahydrate (•7 H20) would the patient require? (Molecular weights: zinc 65, ZnSO4 161, H20 18)

123 mg
220 mg
300 mg
392 mg

The correct answer is: 392 mg

Since the question asks for the equivalent amount of elemental zinc, it is important to consider the molecular weights of the different compounds. Anhydrous zinc sulphate only contains zinc and sulphate, with a molecular weight of 161. However, zinc sulphate heptahydrate also includes 7 molecules of water, with a total molecular weight of 161 + (7x18) = 275. Therefore, to get the same amount of zinc, the amount of zinc sulphate heptahydrate required would be the molecular weight ratio of 65/161 multiplied by the given amount of anhydrous zinc sulphate (220 mg). This would result in 220 * (65/161) = 88.5 mg of elemental zinc. However, since the question asks for the amount of zinc sulphate heptahydrate required, we must