Question

The dot at the end of this sentence has a mass of about one microgram.assuming that the black stuff is carbon,calculate the approximate number of atoms of carbon needed to make such a dot

Answer 1

I microgram means 1 x 10>-6 gm

Now 12 gm carbon = 6.023 x 10>23 atoms

1 x 10> -6 gm = 6.023 x 10>23 / 12 x 1 x 10> -6

= 5.019 x 10 >16

Answer 2

Answer:

The number of atoms of carbon needed to make such a dot is $5.016\times 10^{16}atoms$.

Explanation:

Mass of black dot = $1\mu g$

$1 \mu g=10^{-6} g$

Atomic mass of 1 carbon atom = 12 g/mol

Moles of carbon atom in 1 micro gram:

$\frac{10^{-6} g}{12 g/mol}=8.33\times 10^{-8} moles$

Number carbon atoms in the 1 micro gran dot:

$8.33\times 10^{-8} moles\times 6.022\times 10^{23}=5.016\times 10^{16}atoms$

The number of atoms of carbon needed to make such a dot is $5.016\times 10^{16}atoms$.