The content that adheres to is the problem of great 8. In this lecture us cover the Mole and also Avagadro"s Number and also the calculations for Molar Mass and also conversions utilizing moles.

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The MOLE (mol) is a unit of measurement the is the amount of a pure problem containing the same number of 6294.orgical units (atoms, molecules etc.) together there space atoms in exactly 12 grams of carbon-12 (i.e., 6.022 X 1023).

So the mole is the title supplied for the amount 6.022 x 1023 much the same means the indigenous "dozen" is provided for the amount 12.

So if you had actually a mole that donuts girlfriend would have 6.022 x 1023 donuts and also a major stomach ache.

We usage the mole (mol) to stand for the quantity of building material in 6294.orgistry due to the fact that the numbers of atoms and also molecules in every substance is therefore large. The value offered 6.022 x 1023 is called Avagadro"s number because that the scientist that uncovered the number of atoms in 12 grams that carbon 12. Why usage 12 grams? This is the theoretical atom mass the the Carbon-12 isotope (6 protons and also 6 neutrons). This means that the atom mass or atomic weight (12 grams) of carbon is same to precisely 1 mole of carbon.

Using carbon as a reference, the atom weights you see in the routine table are likewise equal come one mole the those substances:

Lithium for instance has actually an atom mass that 6.941 grams and this is same to one mole of lithium. This is why us state the atomic and also molecular masses in units of grams per mole or g/mol.

What have the right to we perform with moles? We use the unit to make calculations based on balanced 6294.orgical equations. We use the stoichiometry (fancy way of speak mole ratios in an equation) to do predictions about how much product will be make or reactant essential if we know one mole quantity in a reaction.

### Moles that a Substance and the molecule Weight

The Molar mass or Molecular weight (interchangeable terms so long as we space on Earth) of a substance is the complete of every the separation, personal, instance masses of the aspects it contains. To use our old friend water as an example:

One mole of Water is written of 1 mole the Oxygen and two mole of Hydrogen. The fixed of oxygen same to one mole that oxygen is 15.998 grams and also the massive of one mole of hydrogen is 1.008 g. If we complete up the gram amounts of each aspect in the water molecule = 15.998g/mol + 2(1.008g/mol) we obtain the molar mass of water = 18.014g/mol.

So if we had exactly 18.014g the water us would have 1 mole that water.

### Practice: Mole and also Molar Mass

### Mole Relationships

The reason the mole is so important is due to the fact that we usage the mole as the unit for most of the relationships in 6294.orgistry. Reactions are balanced based on the variety of moles that each element in the reaction, systems concentrations are very often described in regards to moles every liter or moles per kg of solvent and also we have currently seen that the molecules or atoms of an aspect are reported together moles of the substance fairly than the individual counting of their particles.

Let"s begin the relationship discussion with the relationship in between the mole and also the AMU.

An AMU is 1/12 the mass of a Carbon-12 atom which follow to the routine table weighs ~12g. This means that 1 AMU ≈ 1g right? and also thus Carbon has actually a fixed of 12amu, correct? but wait, this could not it is in the massive of a solitary carbon atom right? They are really, yes, really tiny. And also that is correct, the mass shown in the periodic table is actually the fixed of 6.022 x 1023 carbon atom or a mole of carbon atoms. So in reality, 1 AMU = 1.66 x 10-24g and also while a carbon atom weighs 12 AMU, the mass shown in the periodic table is

### 12 atom x 1.66 x 10-24g x 6.022 x 1023 atoms/ mol= 12 g/mol

So a single carbon atom weighs 12 amu while a mole the carbon atom weighs 12.01g/mol.

## Mole Calculations

There are plethora the calculations that can be performed using the unit that moles together the intermediate. I am going to testimonial a few of castle now and also then girlfriend will see as we progression through later topics the moles are important to those calculations as well.

See more: Gcf Calculator To Know Greatest Common Factor Of 21 And 39 ?

Typical mole calculations:

1) **Calculation the the Molecular load or Molar massive of a compound**

The molar mass of a compound also often referred to as the molecular load while on Earth, is just the sum of every the individual aspect masses in the compound. You usage the routine table together a recommendation for this masses and total lock up:

For example, if we desire to total the molar mass of Aluminum Sulfate Al2(SO4)3 , we need to identify the number and also mass that each facet in the compound. Because that Aluminum Sulfate the totals room 2 Al, 3 S and 12 O. So below is the math making use of the atom masses provided in the routine table:

### 2(26.98 g/mol) + 3( 32.07 g/mol) + 12(16.00 g/mol) = 342.17 g/mol

2) **Conversion from Grams to moles or mole to Grams**

Once you understand the molar massive of a compound, you deserve to use that mass to identify the amount of mole in a gram quantity of the problem or whereas you can calculate the variety of grams in a mole lot of the substance.

Here room some examples:

How many moles are in 55.4g the Aluminum Sulfate?

The calculation is collection up like a conversion with the molar mass of Aluminum Sulfate together the switch factor:

### 55.4g Al2(SO4)3 x 1 mol Al2(SO4)3/342.17 g Al2(SO4)3 = 0.162 mol Al2(SO4)3

Or, How countless grams of Al2(SO4)3 space in 6.34 moles of Al2(SO4)3?

### 6.34 mol Al2(SO4)3 x 342.17g Al2(SO4)3/ 1 mol Al2(SO4)3 = 2.17 x 103 Al2(SO4)3

3) **Conversion to molecules or Atoms**

In enhancement to gift a unit for molar mass, the mole is additionally the gateway in between the massive of a substance and its atom or molecules.

For Example, if asked how many molecules that Al2(SO4)3 room in th 55.4 g of Al2(SO4)3 over we just need to an initial calculate the number of moles together before and also then use Avagadro"s number to transform the mole to molecules:

### 55.4g Al2(SO4)3 x 1 mol Al2(SO4)3/342.17 g Al2(SO4)3= 0.162 mol Al2(SO4)3

### 0.162 mol Al2(SO4)3 x 6.022 x 1023 molecule Al2(SO4)3/ 1 mol Al2(SO4)3 =

### 9.76 x 1022 **Molecules Al2(SO4)3**

Furthermore if we ongoing the problem and also asked how numerous Aluminum atoms were in the 55.4 g that Al2(SO4)3?

Well that is a straightforward continuation. We simply need to multiply by the number of atoms of Aluminum in the compound:

### 9.76 x 1022 **Molecules Al2(SO4)3** x 2 atom Al/ 1 molecule **Al2(SO4)3** = 1.95 x 1023 Al atoms

Let"s exercise some more: