# Question a6197

Sep 17, 2017

Here's what I would use.

#### Explanation:

I would go with the molar mass of aspirin as the first conversion factor, the mole ratio that exists between aspirin and hydrogen as the second, and Avogadro's constant as the third.

This will allow me to go

$1. \text{ ""grams of aspirin " stackrel(color(white)(acolor(red)("molar mass")aaa))(->) " moles of aspirin}$

$2. \text{ ""moles of aspirin " stackrel(color(white)(acolor(blue)("moles H in aspirin")aaa))(->) " moles of hydrogen}$

$3. \text{ " "moles of hydrogen " stackrel(color(white)(acolor(darkgreen)("Avogadro's constant")aaa))(->) " atoms of hydrogen}$

In your case, you can use the aforementioned conversion factors to say that $\text{1.00 g}$ of aspirin will contain

1.00 color(red)(cancel(color(black)("g"))) * (1 color(blue)(cancel(color(black)("mole aspirin"))))/(180.157color(red)(cancel(color(black)("g")))) * (8 color(darkgreen)(cancel(color(black)("moles H"))))/(1color(blue)(cancel(color(black)("mole aspirin")))) * (6.022 * 10^(23)color(white)(.)"atoms H")/(1 color(darkgreen)(cancel(color(black)("mole H"))))#

$= 2.67 \cdot {10}^{22} \textcolor{w h i t e}{.} \text{atoms H}$

The answer is rounded to three sig figs.