Calculations involving Entities | mole-calculationss

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Formulas

Key Words

Organization

organization is the key to making your calculations simple. These steps below will help you determine calculations involving entities

In general

n = amount in moles (mol)

Nentities = number of entities

NA = Avogadros constant (6.02x10^23 entities/mol)

Some key terms to keep in mind are; (atom) (units) and (molecules). These words suggest you will be finding calculations involving Entities.

Lets take a look

Mole to Nentities calculation

-Taking the (amount)of moles and multiplying it by avagadro's number, to find the number of entities.

Example: Calculate the number of (molecules) present in 2.0 mol of ammonia, NH3.

Step 1. Write out the givens and unknowns

NH3

n = 2.0 mol

NA = 6.02 X10^23(NH3/mol)

NNH3= ?

Step 2. Find out the formula that will give you Nentities. In this case Nentities= n * Na

NNH3= n *NA

NNH3= 2.0mol(6.02x10^23NH3/mol)

** remember that the mol(s) cross eachother out.

Step 3. Calculate you equation

NNH3= 1.2 X10^24 NH3 molecules

Step 4. Make a concluding sentence

Therefore, there is 1.2 x10^24 molecules present in NH3

Nentities to mole calculation

- Taking the (molecules) of Nentities and dividing that by avagadro's number, to find the number moles.

Example: Calculate the amount of substance in 3.01 x 10^23 atoms of copper

Step 1. Write out the givens and unknowns

NCu= 3.01 x 10^23

NA= 6.02 x 10^23 Cu/mol

n = ?

Step 2. Find out the formula that will give you moles. In this case n= Nentities/ NA

n= NCu / NA

n = 3.01 x 10^23 Cu/ 6.02 x 10^23 Cu/mol

** Remember that the Cu cross' eachother out.

Step 3. Calculate you equation

n =0.55 mol

Step 4. Make a concluding sentence

Therefore, there is 0.55 mol in 3.01 x 10^23 atoms of copper.

*** Important***

Remember to use the sig fig laws when rounding your answers!!

Now let try putting what we learned together

Mass to Nentities and Reverse

This step combines everything we have learned in the past lessons. Showing the steps to take to get from mass to Nentities.

Lets break it down

You will need to find these essential products:

Mass, Moles, Molar mass and Nentities.

Step 1. mass / Molar mass gives you moles.

Step 2.( moles x Molar mass gives you mass.)

Step 3. moles x NA gives you Nentities.

Step 4. (Nentities/ NA gives you mole)

The listings above are the fundamental steps to put everything we've learned into action.