Question

Calculate the mass of chloroform that contains 1.00X10^12 molecules of chloroform

Answer 1

Molar mass of chloroform (CHCl3)
C = 1 * 12 = 12 a.m.u
H = 1 * 1 = 1 a.m.u
Cl = 3 * 35.5 = 106.5 a.m.u
 Molar Mass (CHCl3) = 12 + 1 + 106.5 = 119.5 g / mol
 
Knowing that: The value of Avogadro's constant corresponds to approximately $6,02*10^{23}$ molecules, if chloroform contains $1,00 * 10^{12}$ molecules.  
We have:
 
$1,00 * 10^{12} * 6,02 * 10^{23} = 6,02 * 10 ^ {35} molecules$
 
Now, how many grams are there in the chloroform molecule?

grams -------- molecules
119,5 → $6,02 * 10^{23}$
x → $6,02 * 10^{35}$

$6,02 * 10 ^ {23} * x = 119,5 * 6,02 * 10 ^{35}$
$6,02 * 10 ^ {23}x = 719,39 * 10^{35}$
$x = \frac{719,39}{6,02}*10^{35-23}$
$\boxed{x = 119,5*10^{12}grams}$