Calculate the percentage composition of lead(ii chloride (pbcl2. choose the correct percentages for pb and cl.

To do this, what we need to do is find the mass of PbCl2 as a whole, and the masses of Pb and Cl2 on their own.

So, the mass can be found by locating the atomic mass on the periodic table! It is that easy :)

The mass of Pb is 207.2
The mass of Cl2 is 70.906, since the mass is 35.453 and we have two of them.

When we add it together, the total mass of PbCl2 is 278.106, all we need to do is add the two masses we calculated before, together!

The formula for percent composition is:

element mass
x 100
compound mass

So, lets do the % composition of Pb first. 

207.2
 
278.106

When we divide the two and multiply that answer by 100, we get 74.5%. So, the percent composition of Lead is 74.5%.

Now, lets do the same for Cl!

70.906
x 100
278.106

The answer we get for that is 25.5%. So, that is the percent composition of Cl in PbCl2.

Hope I could help! :)

The correct answer is b