# Question 0cc70

Oct 17, 2017

$1 \cdot {10}^{26}$ $\text{protons}$

#### Explanation:

For starters, you know that chlorine has an atomic number equal to $17$, which implies that every atom of chlorine, $\text{Cl}$, has $7$ protons in the nucleus.

Consequently, you can say that every chlorine molecule, ${\text{Cl}}_{2}$, which contains two atoms of chlorine, will have a total of $34$ protons.

All you have to do now is to figure out how many molecules of chlorine are present in your sample. Start by using the molar mass of chlorine gas to calculate the number of moles of chlorine gas present in the sample.

6 color(red)(cancel(color(black)("g"))) * "1 mole Cl"_2/(70.906color(red)(cancel(color(black)("g")))) = "0.0705 moles Cl"_2

Next, use Avogadro's constant to find the number of chlorine molecules present in the sample.

0.0705color(red)(cancel(color(black)("moles Cl"_2))) * (6.022 * 10^(23)color(white)(.)"molecules Cl"_2)/(1color(red)(cancel(color(black)("mole Cl"_2)))) = 4.25 * 10^(22)color(white)(.)"molecules Cl"_2#

Finally, use the fact that one molecule of chlorine contains $34$ protons to say that your sample will contain

$4.25 \cdot {10}^{24} \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{molecules Cl"_2))) * "34 protons"/(1color(red)(cancel(color(black)("molecule Cl"_2)))) = color(darkgreen)(ul(color(black)(1 * 10^26color(white)(.)"protons}}}}$

The answer must be rounded to one significant figure, the number of sig figs you have for the mass of chlorine gas.