Question

Convert particles to moles: 8.3 x 10^20 atoms Cu

Answer 1

Answer:

$\boxed {\boxed {\sf 0.0014 \ mol \ Cu}}$

Explanation:

We are asked to convert particles to moles.

1. Avogadro's Number

1 mole of any substance contains the same number of particles (atoms, molecules, formula units). This is Avogadro's Number or 6.022*10²³.

In this problem, the particles are atoms of copper. So, 1 mole of copper contains 6.022*10²³ atoms of copper

2. Convert Atoms to Moles

Use Avogadro's Number to make a ratio.

$\frac{ 1 \ mol \ Cu}{ 6.022*10^{23} \ atoms \ Cu}$

We are trying to convert 8.3*10²⁰ atoms of copper to moles, so we multiply that value by the ratio.

$8.3*10^{20} \ atoms \ Cu*\frac{ 1 \ mol \ Cu}{ 6.022*10^{23} \ atoms \ Cu}$

The units of "atoms Cu" will cancel.

$8.3*10^{20}\frac{ 1 \ mol \ Cu}{ 6.022*10^{23} }$

Condense the expression into 1 fraction.

$\frac{8.3 *10^{20}}{ 6.022*10^{23} } \ mol \ Cu$

$0.001378279641 \ mol \ Cu$

3. Round

The original measurement of atoms has 2 significant figures, so our answer must have the same. For the number we calculated that is the ten-thousandths place.

• 0.001378279641

The 7 in the hundredth thousandth place tells us to round the 3 up to a 4.

$0.0014 \ mol \ Cu$

8.3*10²⁰ atoms of copper are equal to 0.0014 moles of copper.