# Mole Concept - Video Tutorials & Practice Problems

The **Mole Concept** involves the interconversions between different unit amounts of a substance.

## Mole Concept

**Mole **connects together atoms, ions, molecules and formula units.

## Mole Concept Example 1

## Mole Concept

Converting between moles and particles requires Avogadro's Number:**1 mole = 6.022x10 ^{23 }particles.**

## Mole Concept Example 2

## Mole Concept

## Mole Concept Example 3

## Mole Concept Example 4

Mole also serves to connect mass units to particles.

If a sample of sodium chloride, NaCl, contains 73.1 kg, what is its number of formula units?

^{25}formula units

^{25}formula units

^{26}formula units

^{26}formula units

Calculate the number of oxygen atoms found in 783.9 g NiCl_{2} • 6 H_{2}O.

^{25}O atoms

^{25}O atoms

^{26}O atoms

^{26}O atoms

If the density of water is 1.00 g/mL at 25°C, calculate the number of water molecules found in 1.50 x 10^{3} µL of water.

^{21}molecules

^{22}molecules

^{23}molecules

^{24}molecules

A cylindrical copper wire is used for the fences around a house. The copper wire has a diameter of 0.0750 in. How many copper atoms are found in 5.160 cm piece? The density of copper is 8.96 g/cm^{3}. (V = π • r^{2} • h)

^{22}Cu atoms

^{21}Cu atoms

^{21}Cu atoms

^{22}Cu atoms

The density of the sun is 1.41 g/cm^{3} and its volume is 1.41 x 10^{27} m^{3}. How many hydrogen molecules are in the sun if we assume all the mass is hydrogen gas?

^{56}H

_{2}molecules

^{57}H

_{2}molecules

^{58}H

_{2}molecules

^{59}H

_{2}molecules

## Do you want more practice?

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