end show © copyright pearson prentice hall slide 1 of 40 empirical formulas formaldehyde ch 2 o...
TRANSCRIPT
![Page 1: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/1.jpg)
End Show© Copyright Pearson Prentice Hall
Slide 1 of 40
Empirical Formulas
formaldehyde CH2O(toxic preservative)
acetic acid C2H4O2
(vinegar)
glucose C6H12O6
(simple sugar)
all have the same basic or “empirical” formula
CH2O
![Page 2: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/2.jpg)
End Show
Slide 2 of 40
© Copyright Pearson Prentice Hall
Percent Composition and Chemical Formulas
>empirical formula:
the smallest whole-number ratio of the atoms in a compound.
Examples:
CH3 HO PbO2 C2H6N
Non-Examples:
C2H6 H2O2 Pb2O4 C6H18N3
![Page 3: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/3.jpg)
End Show
Slide 3 of 40
© Copyright Pearson Prentice Hall
Percent Composition and Chemical Formulas
>
Acetylene (C2H2) is a gas used in welder’s torches.
These two compounds of carbon both have the same empirical formula (CH) but different molecular formulas.
Styrene (C8H8) is used in making polystyrene.
![Page 4: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/4.jpg)
© Copyright Pearson Prentice Hall
SAMPLE PROBLEM
Slide 4 of 40
End Show
Percent to Mass
Mass to Mole
Divide by Small
Times ‘till Whole
What is the empirical formula of a compound that is analyzed and found to contain 25.9% N and 74.1% O?
![Page 5: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/5.jpg)
© Copyright Pearson Prentice Hall
SAMPLE PROBLEM
Slide 5 of 40
End Show
What is the empirical formula of a compound that is analyzed and found to contain 25.9% N and 74.1% O?
Percent to Mass
Mass to Mole
Divide by Small
Times ‘till Whole
25.9 g N
74.1 g O
x 1 mol N 14.01 g N
x 1 mol O 16.00 g O
= 1.85 mol N
= 4.63 mol O
________ 1.85
________ 1.85
= 1 N
= 2.5 O
x 2 = 2 N
x 2 = 5 O
N2O5
![Page 6: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/6.jpg)
© Copyright Pearson Prentice Hall
Slide 6 of 40
End Show
Practice Problems
62.1 g C
13.8 g H
24.1 g N
x 1 mol C 12.01 g C
x 1 mol H 1.01 g H
x 1 mol N 14.01 g N
= 5.17 mol C
= 13.66 mol H
= 1.72 mol N
________ 1.72
_________ 1.72
________ 1.72
= 3 C
= 8 H
= 1 N
C3H8N
1,6-diaminohexane is used to make nylon. What is the empirical formula if it is 62.1% C, 13.8% H, and 24.1% N?
![Page 7: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/7.jpg)
End Show© Copyright Pearson Prentice Hall
Slide 7 of 40
Percent Composition and Chemical Formulas
>molecular formula:
a whole-number multiple of the empirical formula of a compound
formaldehyde CH2O
acetic acid C2H4O2
glucose C6H12O6
all have the same empirical formula
CH2O
![Page 8: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/8.jpg)
© Copyright Pearson Prentice Hall
SAMPLE PROBLEM
Slide 8 of 40
End Show
Calculate the molecular formula of a compound with the empirical formula CH4N and a molar mass of 60.0 g/mol.
molecular mass = multiple of emp. form.empirical mass
empirical mass1(C) + 4(H) + 1(N) =
12.01 + 4(1.01) + 14.01 = 30.06 g/mol
60.0 =30.06
1.996 ≈ 2 2 (CH4N) =
C2H8N2
![Page 9: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/9.jpg)
© Copyright Pearson Prentice Hall
SAMPLE PROBLEM
Slide 9 of 40
End Show
Calculate the molecular formula of benzene with the empirical formula CH and a molar mass of 78 g/mol.
molecular mass = multiple of emp. form.empirical mass
empirical mass1(C) + 1(H) =
12.01 + 1.01 = 13.02 g/mol
78 =13.02
5.991 ≈ 6 6 (CH) = C6H6
![Page 10: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/10.jpg)
1. An empirical formula shows the __________ of atoms in a compound.
A. lowest common number
B. highest whole ratio
C. lowest whole number ratio
D. average ratio
Quick Quiz!
![Page 11: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/11.jpg)
2. Which of the following is NOT an empirical formula?
A. CH3
B. H2N
C. CH
D. C3H6
Quick Quiz.
![Page 12: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/12.jpg)
3. True or False:
A molecular formula can be the same as an empirical formula.
True False
Example:
Formaldehyde has theempirical formula CH2O,which is its molecular formula as well.
Quick Quiz.
![Page 13: End Show © Copyright Pearson Prentice Hall Slide 1 of 40 Empirical Formulas formaldehyde CH 2 O (toxic preservative) acetic acid C 2 H 4 O 2 (vinegar)](https://reader035.vdocument.in/reader035/viewer/2022062806/5697bf891a28abf838c89ef0/html5/thumbnails/13.jpg)
Quick Quiz.
4. Determine the molecular formula of a compound that contains 40.0 % C, 6.71 % H, and 53.29 % O by mass and has a molar mass of 60.05 g/mol.
A. C2H4O2
B. CH2O
C. C2H3O
D. C2H4O