# What are the different formulas that define a mole?

##### 4 Answers

There is only one definition of a mole. A mole is the quantity of a substance that has the same number of particles as are found in exactly 12 g of carbon-12. This number, Avogadro's number, is 6.022 × 10²³.

This definition, however, leads to several different methods for determining the number of moles of a substance based on the

Number of particles

Molar mass

Volume and molarity of a solution

Ideal Gas Law

FROM NUMBER OF PARTICLES

n = number of molecules)/Avogadro’s Number

Example:

How many moles of oxygen are contained in 2.25 x 10²⁴ molecules?

n = number of molecules/Avogadro’s Number =

2.25 × 10²⁴ molecules × (1 mol)/(6.022 × 10²³ molecules) = 3.74 mol

FROM MOLAR MASS

n =

Example:

How many moles are in 98.0 g MnO₂?

n =

FROM VOLUME AND MOLARITY OF A SOLUTION

n = volume × molarity or

n = litres × moles/litres

Example:

How many moles of aluminum nitrate, Al(NO₃)₃, are in 3.00 L of a 0.340 mol/L solution of aluminum nitrate?

n = 3.00 L Al(NO₃)₃ ×

FROM THE IDEAL GAS LAW

n =

Example:

Calculate the number of moles of hydrogen gas in an 80.5 mL sample collected at 25 °C and 0.976 atm.

n =

3.21 × 10⁻³ mol

There are, of course, other methods for determining the number of moles, but these are the most common methods that are used in the early stages of chemistry.

There is only one definition of a mole. A mole is the quantity of a substance that has the same number of particles as are found in exactly 12 g of carbon-12. This number, Avogadro's number, is 6.022 × 10²³.

This definition, however, leads to several different methods for determining the number of moles of a substance based on the

Number of particles

Molar mass

Volume and molarity of a solution

Ideal Gas Law

FROM NUMBER OF PARTICLES

n = number of molecules/Avogadro’s Number

Example:

How many moles of oxygen are contained in 2.25 x 10²⁴ molecules?

n = number of molecules/Avogadro’s Number =

2.25 × 10²⁴ molecules × (1 mol)/(6.022 × 10²³ molecules) = 3.74 mol

FROM MOLAR MASS

n =

Example:

How many moles are in 98.0 g MnO₂?

n =

FROM VOLUME AND MOLARITY OF A SOLUTION

n = volume × molarity or

n = litres × moles/litres

Example:

How many moles of aluminum nitrate, Al(NO₃)₃, are in 3.00 L of a 0.340 mol/L solution of aluminum nitrate?

n = 3.00 L Al(NO₃)₃ ×

FROM THE IDEAL GAS LAW

n =

Example:

Calculate the number of moles of hydrogen gas in an 80.5 mL sample collected at 25 °C and 0.976 atm.

n =

3.21 × 10⁻³ mol

There are, of course, other methods for determining the number of moles, but these are the most common methods that are used in the early stages of chemistry.

There is only one definition of a mole. A mole is the quantity of a substance that has the same number of particles as are found in exactly 12 g of carbon-12. This number, Avogadro's number, is 6.022 × 10²³.

This definition, however, leads to several different methods for determining the number of moles of a substance based on the

Number of particles

Molar mass

Volume and molarity of a solution

Ideal Gas Law

FROM NUMBER OF PARTICLES

n = number of molecules/Avogadro’s Number

Example:

How many moles of oxygen are contained in 2.25 x 10²⁴ molecules?

n = number of molecules/Avogadro’s Number =

2.25 × 10²⁴ molecules × (1 mol)/(6.022 × 10²³ molecules) = 3.74 mol

FROM MOLAR MASS

n = mass/molar mass

Example:

How many moles are in 98.0 g MnO₂?

n =

FROM VOLUME AND MOLARITY OF A SOLUTION

n = volume × molarity or

n = litres × moles/litres

Example:

How many moles of aluminum nitrate, Al(NO₃)₃, are in 3.00 L of a 0.340 mol/L solution of aluminum nitrate?

n = 3.00 L Al(NO₃)₃ ×

FROM THE IDEAL GAS LAW

n =

Example:

Calculate the number of moles of hydrogen gas in an 80.5 mL sample collected at 25 °C and 0.976 atm.

n =

3.21 × 10⁻³ mol

There are, of course, other methods for determining the number of moles, but these are the most common methods that are used in the early stages of chemistry.

Number of particles

Molar mass

Volume and molarity of a solution

Ideal Gas Law

FROM NUMBER OF PARTICLES

n = number of particles/Avogadro’s Number

Example:

How many moles of oxygen are contained in 2.25 x 10²⁴ molecules?

n = number of molecules/Avogadro’s Number =

2.25 × 10²⁴ molecules × (1 mol/6.022 × 10²³ molecules) = 3.74 mol

FROM MOLAR MASS

n =

Example:

How many moles are in 98.0 g MnO₂?

n =

FROM VOLUME AND MOLARITY OF A SOLUTION

n = volume × molarity or

n = litres × moles/litres

How many moles of aluminum nitrate, Al(NO₃)₃, are in 3.00 L of a 0.340 mol/L solution of aluminum nitrate?

n = 3.00 L Al(NO₃)₃ ×

FROM THE IDEAL GAS LAW

n =

Calculate the number of moles of hydrogen gas in an 80.5 mL sample collected at 25 °C and 0.976 atm.

n =

3.21 × 10⁻³ mol