Question c440b

Sep 6, 2016

$\text{0.12 g}$

Explanation:

Your strategy here will be to use three conversion factors: one to take you from teaspoons to milliliters, one to take you from milliliters to milligrams, and one to take you from milligrams to grams.

The problem tells you that

$\textcolor{p u r p \le}{\overline{\underline{| \textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{\text{1 teaspoon " = " 5 mL}} \textcolor{w h i t e}{\frac{a}{a}} |}}}$

Use this to determine the volume of this drug that would be equivalent to $1.2$ teaspoons

1.2 color(red)(cancel(color(black)("teaspoons"))) * "5 mL"/(1color(red)(cancel(color(black)("teaspoon")))) = "6.0 mL"

Next, the problem tells you that every $\text{5 mL}$ of this drug contains $\text{100. mg}$ of ibuprofen. This means that your sample will contain

6.0 color(red)(cancel(color(black)("mL drug"))) * "100. mg ibuprofen"/(5color(red)(cancel(color(black)("mL drug")))) = "120 mg ibuprofen"

Finally, use the fact that

$\textcolor{p u r p \le}{\overline{\underline{| \textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{\text{1 g" = 10^3"mg}} \textcolor{w h i t e}{\frac{a}{a}} |}}}$

to find the amount of ibuprofen in grams

120 color(red)(cancel(color(black)("mg"))) * "1 g"/(10^3color(red)(cancel(color(black)("mg")))) = color(green)(bar(ul(|color(white)(a/a)color(black)("0.12 g")color(white)(a/a)|)))#

I'll leave the answer rounded to two sig figs.