Question

Each 5-mL portion of Maalox contains 400 mg of magnesium hydroxide, and 40 mg of simethicone. If the recommended dose is 2 teaspoons 4 times a day, how many grams of each substance would an individual take in a 24-hour period? (1 teaspoon= 5 mL)

Answer 1

Your patient would get 8 times more magnesium hydroxide and simethicone than a teaspoon contains.

So, you know that you have `"5-mL"` portions of your drug to work with. The recommended dosage is two teaspoons, or two `"5-mL"` doses, 4 times a day.Since a day has 24 hours, this will mean that your patient gets 2 teaspoons every 6 hours.

This means that, during a 24-hour period, your patient will get

`"24 hours" * "2 teaspoons"/"6 hours" = "8 teaspoons"`

Since a teaspoon holds `"5-mL"` of your drug, the amounts of magnesium hydroxide and simethicone he'll get are

`"8 teaspoons" * "5 mL"/"1 teaspoon" * "400 mg"/"5 mL" = "3200 mg "` `Mg(OH)_2`

and

`"8 teaspoons" * "5 mL"/"1 teaspoon" * "40 mg"/"5 mL" = "320 mg simethicone"`

If you these values to one sig fig, the number of sig figs in 5 mL, 400 mg, and 40 mg, the answer will be

`m_(Mg(OH)_2) = "3000 mg "` and

`m_("simethicone") = "300 mg"`

Since you must give the answer in grams, use a simple conversion factor to go from mg to g

`"3000 mg "Mg(OH)_2 * "1 g"/"1000 mg" = "3 g "` `Mg(OH)_2`

and

`"300 mg simethicone" * "1 g"/"1000 mg" = "0.3 g simethicone"`