Download NO2 N2O4 Mini-Lesson: Empirical Formula: o NO2 or N2O4

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Name: ____________________________________
KIPP NYC College Prep
Period: ________
Date: ___________________
General Chemistry
UNIT 7: Chemical Reactions
Lesson 5: Empirical vs. Molecular formulas!
By the end of today, you will have an answer to:
What are empirical and molecular formulas?
Do Now:
Consider the following two compounds. NO2 and N2O4
 Are these compounds ionic or covalent? Explain in-terms of electrons.
NO2
N2O4
Name:
Name:
Draw a particle diagram of 2NO2
Draw a particle diagram of N2O4
Explain one similarity and one difference between 2NO2 and N2O4.
Mini-Lesson: Empirical Formula:

A compound whose elements are found in the simplest whole number ratio. Used in covalentlybonded molecules.
Circle the compound that appears as an empirical formula:
o NO2 or
N2O4
Explain your reasoning:
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Circle the compound in the pair that is found in an empirical formula:
CH2O
or
C3H6O3
P2O4
or
PO2
C4H10O2N4
or
C2H5ON2
Write the empirical formula for the following compounds:
N2O6
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P3O6
_____________________________ C11H22O11 __________________________
***Ionic compounds are always found in an empirical formula.
Example: NaCl vs. Na2Cl2
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PRACTICE TIME!
Directions:
Determine the empirical formula for the following compounds.
1. C3O6
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2. N3H9
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3. C6H12O6
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4.
5. What is the empirical formula of a compound that has a carbon-to-hydrogen ratio of 2 to 6?
(1) CH3
(3) C3H
(2) C2H6
(4) C6H2
6. The compounds C2H4 and C4H8 have the same
(1) freezing point at standard pressure
(2) boiling point at standard pressure
(3) molecular formula
(4) empirical formula
7.
8. Determine the empirical formula of C2H8N4O2. [1]
***Challenge: Sucrose, or table sugar is C12H22O11.
 Determine the empirical formula.
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Refresher: Types of Reactions!
9. In which type of reaction does a single reactant break down into two or more substances?
(1) Synthesis
(2) Decomposition
(3) Single replacement
(4) Double replacement
10. Which type of reaction does the following represent: Fe + 2 HCl  FeCl2 + H2
(1) Synthesis
(2) Decomposition
(3) Single replacement
(4) Double replacement
Refresher: Law of Conservation of Mass!
11. In an experiment, 3.67 grams of lead completely reacts with oxygen, producing 5.25 grams of lead (II)
oxide.
Determine the total mass of oxygen consumed.
12. Which equation shows conservation of atoms?
(1) 2N2 + O2  2N2O
(2) 2N2 + 2O2  2N2O
(3) N2 + O2  N2O
(4) N2 + O2  2N2O
13. Given the balanced equation representing a reaction:
CaCl2 (s)  Ca (s) + Cl2 (g)
What is the total mass of CaCl2 (s) that produces 60 grams of Ca(s) and 34 grams of Cl2(g)?
(1) 36 g
(3) 26 g
(2) 60 g
(4) 94 g
More practice Balancing Equations!
14.
____ CaCl2  ____ Ca + ____ Cl2
15.
____ Sn + ____ Cl2  ____ SnCl4
Type of reaction: _____________________________________________
Type of reaction: _____________________________________________
16.
17.
____ FeO  ____ Fe + ____ O2
Type of reaction: _____________________________________________
____ Fe + ____ HCl  ____ FeCl2 + ____ H2
Type of reaction: _____________________________________________
18. _______Ca(OH)2 + _______ NH4Cl  _______NH4OH + _______ CaCl2
Type of reaction: _____________________________________________
19. _______Pb(NO3)2 + _______NaI  _______PbI2 + _______NaNO3
Type of reaction: _____________________________________________
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ADDITIONAL PRACTICE:
5.
____ SnO2 + ____ C  ____ Sn + ____ CO
6. ____ H2O  ____ H2 + ____ O2
Type of reaction: _____________________________________________
Type of reaction: _____________________________________________
7. ___ PbO + ____ H2S  ____ PbS + ____ H2O
8. ____ N2 + ____ O2  ____ N2O5
Type of reaction: _____________________________________________
Type of reaction: _____________________________________________
9. _____ K + _____CaO  ________K2O + _______Ca
10. _______ SnO2 + _______H2  ________ Sn + _________ H2O
Type of reaction: _____________________________________________
Type of reaction: _____________________________________________
Conclusion:
1) Why does the number of atoms have to be equal on both sides of the chemical equation?
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2) Why can’t you change the number of atoms in an equation by modifying the subscript?
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3) Explain the difference between 2CO2 and 1C2O4. Answer which one is empirical.
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