Question

How many moles of iron are in a sample that contain 7.91x10^23 atoms of iron

Answer 1

1.31 mol Fe

Step-by-step explanation:

I hope this helps!!!!

Answer 2

`\boxed {\boxed {\sf 1.31 \ mol \ Fe}}`

Step-by-step explanation:

We are asked to find how many moles of iron are in a sample containing 7.91×10²³ atoms of iron (Fe).

We convert atoms to moles using Avogadro's Number of 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are atoms of iron. There are 6.022 ×10²³ atoms of iron in 1 mole of iron.

Convert using dimensional analysis and set up a conversion factor using the molar mass.

`\frac { 6.022 * 10^(23) \ atoms \ Fe}{ 1 \ mol \ Fe}`

We are converting 7.91 ×10²³ atoms of iron to moles, so we multiply by this value.

`7.91 * 10^(23) \ atoms \ Fe *\frac { 6.022 * 10^(23) \ atoms \ Fe}{ 1 \ mol \ Fe}`

Flip the ratio so the units of atoms of iron cancel.

`7.91 * 10^(23) \ atoms \ Fe *\frac { 1 \ mol \ Fe}{ 6.022 * 10^(23) \ atoms \ Fe}`

`7.91 * 10^(23) *\frac { 1 \ mol \ Fe}{ 6.022 * 10^(23) }`

`\frac { 7.91 * 10^(23)}{ 6.022 * 10^(23) } \ mol \ Fe`

`1.313517104 \ mol \ Fe`

The original value of atoms of iron has 3 significant figures, so our answer must have the same. For the number we found, that is the hundredth place. The 3 in the thousandth place tells us to leave the 1 in the hundredth place.

`1.31 \ mol \ Fe`

There are approximately 1.31 moles of iron in 7.91×10²³ atoms of iron.