Purity, formulations and chromatography

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Question 8
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This question is about calcium carbonate tablets, which are commonly used as dietary supplements.

Calcium carbonate contains calcium ions (Ca2+Ca^{2+}Ca2+) and carbonate ions (CO32−CO_3^{2-}CO32−​).

a.

A student wants to test a calcium carbonate tablet to confirm the presence of both calcium ions and carbonate ions. They are provided with:

  • a metal wire
  • dilute hydrochloric acid
  • limewater

Plan an investigation to show the presence of calcium ions and carbonate ions in the tablet. You should include the expected results of the tests for both ions.

[6]
b.

The tablet also contains other substances like binders and flavorings. These substances are present in fixed, carefully chosen amounts to make sure the tablet is safe and effective. What name is given to mixtures designed as a useful product, like tablets?

[1]
c.

A tablet has a mass of 1.50 g1.50\text{ g}1.50 g and contains 550 mg550\text{ mg}550 mg of calcium carbonate. Calculate the percentage by mass of calcium carbonate in this tablet. Give your answer to 3 significant figures.

[3]

Purity, formulations and chromatography Questions

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