Question

What is the mass, in grams, of a sample of 1.20 × 1022 atoms of mercury (Hg)? Show your work or explain the steps that you used to determine your answer.

Answer 1

Answer: 3.81 grams

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 Liters at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given atoms}}{\text {Avogadro's number}}$

$\text{Number of moles}=\frac{1.20\times 10^{22}}{6.023\times 10^{23}}=0.019moles$   (1L=1000ml)

Now 1 mole of $Hg$ atom weighs = 200.59 g

0.019 moles of $Hg$ atom weighs= $\frac{200.59}{1}\times 0.019=3.81g$

Thus mass of sample of mercury is 3.81 grams

Answer 2

Atomic mass Hg = 200.59 u.m.a

200.59 g --------------- 6.02x10²³ atoms
( mass Hg ) ----------- 1.20 x10²² atoms

mass Hg = ( 1.20x10²² ) x 200.59 / 6.02x10²³

mass Hg = 2.407x10²⁴ / 6.02x10²³

= 3.998 g of Hg

hope this helps!