Grams Per Mole Of Oxygen
The Mole
The content that follows is the substance of lecture 8. In this lecture we cover the Mole and Avagadro's Number as well as the calculations for Molar Mass and conversions using moles.
The MOLE (mol) is a unit of measurement that is the corporeality of a pure substance containing the same number of chemical units (atoms, molecules etc.) as there are atoms in exactly 12 grams of carbon-12 (i.east., vi.022 10 1023).
So the mole is the title used for the corporeality 6.022 x ten23 much the same way the word "dozen" is used for the amount 12.
And then if you had a mole of donuts yous would have 6.022 10 ten23 donuts and a serious stomach anguish.
Nosotros use the mole (mol) to represent the amount of substances in chemical science because the numbers of atoms and molecules in each substance is and so large. The value given half dozen.022 x 1023 is chosen Avagadro's number for the scientist that found the number of atoms in 12 grams of carbon 12. Why employ 12 grams? This is the theoretical atomic mass of the Carbon-12 isotope (half-dozen protons and half dozen neutrons). This means that the atomic mass or atomic weight (12 grams) of carbon is equal to exactly 1 mole of carbon.
Using carbon as a reference, the atomic weights you lot run across in the periodic tabular array are also equal to i mole of those substances:
Lithium for example has an atomic mass of vi.941 grams and this is equal to one mole of lithium. This is why we state the atomic and molecular masses in units of grams per mole or thou/mol.
What can nosotros practise with moles? We utilise the unit of measurement to brand calculations based on balanced chemical equations. We utilise the stoichiometry (fancy way of proverb mole ratios in an equation) to brand predictions about how much product volition exist made or reactant needed if nosotros know one mole amount in a reaction.
Moles of a Substance and the Molecular Weight
The Molar mass or Molecular Weight (interchangeable terms so long as we are on Earth) of a substance is the total of all the individual masses of the elements it contains. To utilise our onetime friend water as an case:
One mole of Water is equanimous of ane mole of Oxygen and two moles of Hydrogen. The mass of oxygen equal to ane mole of oxygen is xv.998 grams and the mass of one mole of hydrogen is 1.008 chiliad. If we total upward the gram amounts of each element in the h2o molecule = fifteen.998g/mol + 2(1.008g/mol) we get the tooth mass of water = xviii.014g/mol.
So if we had exactly 18.014g of water we would have 1 mole of water.
Practice: Mole and Molar Mass
Mole Relationships
The reason the mole is so important is because nosotros use the mole as the unit of measurement for most of the relationships in chemistry. Reactions are balanced based on the number of moles of each element in the reaction, solution concentrations are very oftentimes described in terms of moles per liter or moles per kg of solvent and we have already seen that the molecules or atoms of an chemical element are reported every bit moles of the substance rather than the individual count of their particles.
Allow'due south start the relationship word with the relationship between the mole and the AMU.
An AMU is one/12 the mass of a Carbon-12 atom which co-ordinate to the periodic table weighs ~12g. This ways that 1 AMU ≈ 1g correct? and thus Carbon has a mass of 12amu, right? Simply look, this could not be the mass of a single carbon cantlet right? They are really, really tiny. And that is correct, the mass shown in the periodic tabular array is actually the mass of 6.022 x 1023 carbon atoms or a mole of carbon atoms. And so in reality, one AMU = 1.66 x 10-24g and while a carbon atom weighs 12 AMU, the mass shown in the periodic table is
12 atoms x one.66 x 10-241000 x half dozen.022 10 x23 atoms/ mol= 12 g/mol
So a unmarried carbon atom weighs 12 amu while a mole of carbon atoms weighs 12.01g/mol.
Mole Calculations
There are plethora of calculations that can be conducted using the unit of measurement of moles as the intermediate. I am going to review a few of them now and and so you will see every bit we progress through later topics that moles are essential to those calculations as well.
Typical mole calculations:
one) Adding of the Molecular Weight or Molar Mass of a compound
The molar mass of a compound as well often called the molecular weight while on Earth, is simply the sum of all the private element masses in the compound. You lot use the periodic tabular array as a reference for these masses and total them upward:
For instance, if we desire to total the tooth mass of Aluminum Sulfate Al2(So4)3 , nosotros need to determine the number and mass of each element in the compound. For Aluminum Sulfate the totals are two Al, three Southward and 12 O. So here is the math using the diminutive masses given in the periodic table:
2(26.98 g/mol) + 3( 32.07 chiliad/mol) + 12(16.00 g/mol) = 342.17 g/mol
2) Conversion from Grams to Moles or Moles to Grams
In one case you know the molar mass of a chemical compound, you tin can utilise that mass to determine the corporeality of moles in a gram corporeality of the substance or conversely, you can summate the number of grams in a mole amount of the substance.
Hither are some examples:
How many moles are in 55.4g of Aluminum Sulfate?
The calculation is set up like a conversion with the tooth mass of Aluminum Sulfate as the conversion factor:
55.4g Alii(And so4)3 10 1 mol Altwo(SOfour)3/342.17 one thousand Al2(SOfour)3 = 0.162 mol Al2(SOfour)3
Or, How many grams of Al2(SOiv)3 are in 6.34 moles of Al2(Sofour)3?
6.34 mol Altwo(SOfour)iii x 342.17g Al2(SOiv)iii/ 1 mol Al2(And then4)3 = 2.17 x xiii Al2(Then4)3
three) Conversion to Molecules or Atoms
In addition to being a unit for molar mass, the mole is also the gateway between the mass of a substance and its atoms or molecules.
For Example, if asked how many molecules of Al2(And then4)3 are in th 55.4 thou of Alii(SOiv)3 higher up we merely need to first calculate the number of moles as before so use Avagadro's number to convert the moles to molecules:
55.4g Al2(Then4)iii x ane mol Alii(So4)3/342.17 grand Al2(And so4)iii= 0.162 mol Al2(SOiv)3
0.162 mol Alii(SO4)3 x half-dozen.022 10 x23 molecules Al2(SOiv)iii/ 1 mol Al2(SO4)three =
9.76 x 1022 Molecules Al2(So4)three
Furthermore if nosotros connected the problem and asked how many Aluminum atoms were in the 55.iv g of Al2(SO4)3?
Well that is a elementary continuation. We just demand to multiply past the number of atoms of Aluminum in the compound:
9.76 x 1022 Molecules Al2(So4)three x 2 atoms Al/ i molecule Al2(So4)3 = one.95 x 1023 Al atoms
Let'due south Practice some more:
Grams Per Mole Of Oxygen,
Source: https://www.chem.fsu.edu/chemlab/chm1045/mole.html#:~:text=The%20mass%20of%20oxygen%20equal,of%20hydrogen%20is%201.008%20g.
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