let’s use those mole conversions!. empirical formula tells you the lowest ratio of atoms within a...
TRANSCRIPT
![Page 1: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/1.jpg)
Empirical and Molecular Formulas
Let’s use those mole conversions!
![Page 2: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/2.jpg)
Empirical formula tells you the lowest ratio of atoms within a molecule
Molecular formula tells you the actual ratio of atoms within a molecule
The empirical formula CAN equal the molecular formula, but it doesn’t have to.
Empirical and Molecular Formulas
![Page 3: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/3.jpg)
Example:
A compound contains 39.99% carbon, 6.73% hydrogen, and 53.28% oxygen. The molar mass is 180.18 g/mol. What is the empirical and molecular formulas for this compound?
Empirical and Molecular Formulas
![Page 4: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/4.jpg)
Step 1: ◦ Convert grams to moles
(If the problem gives you percents, assume that you have 100g of sample and use the percents as grams)
Empirical and Molecular Formulas
C:
H:
O:
![Page 5: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/5.jpg)
Step 2: ◦ Divide all of the moles from Step 1 by the lowest
number of moles from Step 1.
Empirical and Molecular Formulas
C:
H:
O:
Lowest #
![Page 6: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/6.jpg)
Step 2: ◦ Divide all of the moles from Step 1 by the lowest
number of moles from Step 1.
Empirical and Molecular Formulas
C: = 1
H:
O:
These numbers tell you howmany of each atom you have in the molecule.
![Page 7: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/7.jpg)
Sometimes you may end up with non-whole numbers in Step 2. If this happens:
◦multiply all of the moles by 2 if any end in .5
◦multiply all of the moles by 3 if any end in .3
Empirical and Molecular Formulas
![Page 8: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/8.jpg)
Step 3: ◦ Write the formula using the numbers found in
Step 2.
Empirical and Molecular Formulas
C: = 1
H:
O:
CH2O
This is the empirical formula:
![Page 9: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/9.jpg)
If the problems asks for molecular formula, move on to Step 4:◦ Find the molar mass of the empirical formula and
divide the GIVEN molar mass by this number.
Empirical and Molecular Formulas
Molar mass of empirical formula:CH2O12.01g + 2*1.01g + 16.00g = 30.03 g/mol
GIVEN molar mass = 180.18 g/mol
180.18𝑔/𝑚𝑜𝑙30.03𝑔 /𝑚𝑜𝑙
=6
multiplier
![Page 10: Let’s use those mole conversions!. Empirical formula tells you the lowest ratio of atoms within a molecule Molecular formula tells you the actual](https://reader036.vdocuments.us/reader036/viewer/2022082610/56649da15503460f94a8da52/html5/thumbnails/10.jpg)
Step 5: ◦ Multiply the number of atoms in the empirical
formula by the multiplier.
Empirical and Molecular Formulas
180.18𝑔/𝑚𝑜𝑙30.03𝑔 /𝑚𝑜𝑙
=6
multiplier
(CH2O) * 6 =
C6H12O6This is the molecular formula.