3. Chemical Reactions

Molecular Formula

Introduction to Combustion Analysis, Empirical Formula & Molecular Formula Problems

Which molecular scale image best represents the ionic com-pound that forms between cesium and chlorine? (Cesium is represented by red circles, and chlorine is represented by blue circles.) (LO 6.12)
(a) <img src="" alt="" />
(b) <img src="" alt="" />
(c) <img src="" alt="" />
(d) <img src="" alt="" />

Write the molecular and structural formulas for the compounds
represented by the following molecular models:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/73d5092c4e3489c9-1660585158144.jpg" alt="" />

From the given molar mass and empirical formula of several 
compounds, find the molecular formula of each compound. 
a. C4H9, 114.22 g/mol

What is the molecular formula of each of the following 
compounds? 
(b) empirical formula OH, molar mass 5 34.0 g/mol

What is the molecular formula for the following compound?&nbsp;Empirical Formula:&nbsp;NPCl2&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Molar Mass:347.64 g/mol

Practice Problem: Empirical and Molecular Formulas

Molecular Formula Example 1

C21H30O5

C21H26O5

C18H24O2

Cortisol (MW = 362.47 g/mol), a known steroid hormone, is found to contain 69.6% carbon, 8.34% hydrogen, and 22.1% oxygen by mass. What is its molecular formula?

 Correct, the systematic name for this compound is nitrogen monoxide. 

 This is the correct name and formula for this covalent compound. 

disulfur pentafluoride, S2F5

 Review the rules for writing formulas and naming covalent compounds. 

 Which of the following names and formulas are NOT paired correctly? 

Write the molecular and structural formulas for the compounds 
represented by the following models:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/9fda331028ca8ce2-1660585266176.jpg" alt="" />

From the molecular structures shown here, identify the one
that corresponds to each of the following species: (a) chlorine
gas; (b) propane; (c) nitrate ion; (d) sulfur trioxide;
(e) methyl chloride, CH3Cl.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/739fc904a56ffa08-1660732532291.jpg" alt="" />

 Correct, nitrogen exists as diatomic molecules. 

 Molecular elements do not normally exist in nature with single atoms as their basic units. 

 Which of the following is a molecular element? 

The following ball-and-stick molecular model is a representation
of acetaminophen, the active ingredient in such over-thecounter
headache remedies as Tylenol. 1Red = O, gray = C,
blue = N, ivory = H.2
(a) What is the formula of acetaminophen?

Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order.
(c) Acetic acid (vinegar)

b) Given the mass spectrum of benzene, identify the molec-ular weight and give the molecular formula. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/0908cde407ea023d-1668698459654.jpg" alt="" />

Determine the empirical and molecular formulas of each of
the following substances:
(a) Styrene, a compound used to make Styrofoam® cups and
insulation, contains 92.3% C and 7.7% H by mass and
has a molar mass of 104 g/mol.

A compound of molar mass 177 g>mol contains only carbon,
hydrogen, bromine, and oxygen. Analysis reveals that the compound
contains eight times as much carbon as hydrogen by
mass. Find the molecular formula.

Cinnamaldehyde is a compound that is responsible for the 
characteristic aroma of cinnamon. It contains 81.79% C, 
6.10% H, and the remaining is oxygen. Its molar mass is 
132 g/mol. Determine its molecular formula.

Empirical Formula & Molecular Formula Determination From Percent Composition

An unknown liquid is composed of 34.31% C, 5.28% H, and 60.41% I. The molecular weight found by mass spectrometry is 210.06. What is the molecular formula of the compound?

A pulverized rock sample believed to be pure calcium carbonate, CaCO3, is subjected to chemical analysis and found to contain 51.3% Ca, 7.7% C, and 41.0% O by mass. Why can’t this rock sample be pure CaCO3?

Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order.
(b) Ethylene glycol (automobile antifreeze)

Write a chemical formula for each molecular model.
(See Appendix IIA for color codes.)
(c) <img src="https://lightcat-files.s3.amazonaws.com/problem_images/8e71d6ad100b4840-1659719297484.jpg" alt="" />

Lactic acid, a compound found both in sour milk and in tired muscles, has the structure shown. What is its chemical formula?

Calculating Molecular Formula from Empirical Formula

Write a chemical formula for each molecular model. 
(See Appendix IIA for color codes.)
(a)

Fluoxetine, marketed as an antidepressant under the name Prozac, can be represented by the following ball-and-stick molecular model. Write the molecular formula for fluoxetine, and calculate its molecular weight. (Red = O, gray = C, blue = N, yellow green = F, ivory = H.)

Combustion analysis of a 13.42-g sample of equilin (which contains
only carbon, hydrogen, and oxygen) produces 39.61 g CO2
and 9.01 g H2O. The molar mass of equilin is 268.34 g>mol.
Find its molecular formula.

Fructose is a common sugar found in fruit. Elemental analysis of
fructose gives the following mass percent composition:
C 40.00%, H 6.72%, O 53.28%. The molar mass of fructose is
180.16 g>mol. Find the molecular formula of fructose.

Glycine, an amino acid used by organisms to make proteins,
is represented by the following molecular model.
(a) Write its molecular formula.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/890f0e380acb8883-1660583547062.jpg" alt="" />

Disilane, Si2Hx, is analyzed and found to contain 90.28% silicon by mass. What is the value of x?

Write a ratio showing the relationship between the molar 
amounts of each element for each compound. (See Appendix 
IIA for color codes.) 
(b) <img src="https://lightcat-files.s3.amazonaws.com/problem_images/4fe2a5458ff19109-1662571206047.jpg" alt="" />

(b) An elemental analysis of
the acid indicates that it is composed of 5.89% H, 70.6% C, and
23.5% O by mass. What is its molecular formula?

Determine the empirical and molecular formulas of each
of the following substances:
(a) Ibuprofen, a headache remedy, contains 75.69% C,
8.80% H, and 15.51% O by mass and has a molar mass
of 206 g/mol.

The stimulant amphetamine contains only carbon, hydrogen, and nitrogen. Combustion analysis of a 42.92 mg sample of amphetamine gives 37.187 mg of H2O and 125.75 mg of CO2. If the molar mass of amphetamine is less than 160 g/mol, what is its molecular formula?

Empirical Formula and Molecular Formula Introduction

Lactic acid forms in muscle tissue after strenuous exercise. Elemental analysis shows that lactic acid is 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen by mass. If the molec-ular weight of lactic acid is 90.08, what is the molecular for-mula? (LO 3.11) 
(a) CH2O 
(b) C3H6O3
(c) C4H8O4 
(d) C4H10O2

The following ball-and-stick molecular model is a representation
of thalidomide, a drug that causes birth defects when
taken by expectant mothers but is valuable for its use against
leprosy. The lines indicate only the connections between atoms,
not whether the bonds are single, double, or triple. 1Red = O,
gray = C, blue = N, ivory = H.2
(a) What is the formula of thalidomide?

Ball-and-stick representations of benzene, a colorless liquid
often used in organic chemistry reactions, and acetylene, a gas
used as a fuel for high-temperature welding, are shown below.
(a) Determine the molecular formula of each.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/4712cc5c9a249a59-1660584888345.jpg" alt="" />

A certain metal sulfide, MS2, is used extensively as a high-temperature lubricant. If MS2 is 40.06% sulfur by mass, what is the identity of the metal M?

From the given molar mass and empirical formula of several
compounds, find the molecular formula of each compound.
b. CCl, 284.77 g/mol

CO2 is a molecular compound.

H2O is a molecular compound.

C3H8 is a molecular compound.

 All of the above are examples of molecular compounds. 

 One of the choices is an element rather than a compound. 

 Molecular compounds are composed of two or more different covalently bonded nonmetal atoms. 

 Which of the following is NOT a molecular compound? 

Calculating Molecular Formulas Step by Step | How to Pass Chemistry

Determine the empirical and molecular formulas of each of
the following substances:
(b) Caffeine, a stimulant found in coffee, contains 49.5% C,
5.15% H, 28.9% N, and 16.5% O by mass and has a molar
mass of 195 g/mol.

What is the molecular formula of each of the following 
compounds? 
(b) empirical formula NH2, molar mass 5 32.0 g/mol

C10H14O2

C12H16O4

Elemental analysis of a pure compound indicated that the compound had 72.2% C, 8.50% H and the remainder as O. If 0.250 moles of the compound weighs 41.55 g, what is the molecular formula of the compound?

Determine the empirical and molecular formulas of each of 
the following substances: 
(c) Monosodium glutamate (MSG), a flavor enhancer in 
certain foods, contains 35.51% C, 4.77% H, 37.85% O, 
8.29% N, and 13.60% Na, and has a molar mass of 
169 g/mol.

Ethylene glycol, commonly used as automobile antifreeze, contains only carbon, hydrogen, and oxygen. Combustion analysis of a 23.46 mg sample yields 20.42 mg of H2O and 33.27 mg of CO2. What is the empirical formula of ethylene glycol? What is its molecular formula if it has a molecular weight of 62.0?

In the following drawings, red spheres represent cations, and blue spheres represent anions. Match the drawings (a)–(d) with the following ionic compounds: 
(i) Ca3(PO4)
(ii) Li2CO32
(iii) FeCl2 (a)
(iv) MgSO4

(a) <img src="https://lightcat-files.s3.amazonaws.com/problem_images/d186c85f6747da04-1668556748732.jpg" alt="" />
(b) <img src="https://lightcat-files.s3.amazonaws.com/problem_images/7a0d134c6a135aef-1668556728343.jpg" alt="" />
(c) <img src="" alt="" />
(d) <img src="" alt="" />

Determine the empirical and molecular formulas of each
of the following substances:
(b) Cadaverine, a foul-smelling substance produced by
the action of bacteria on meat, contains 58.55% C,
13.81% H, and 27.40% N by mass; its molar mass is
102.2 g/mol.

An unknown liquid is composed of 5.57% H, 28.01% Cl, and 66.42% C. The molecular weight found by mass spectrometry is 126.58. What is the molecular formula of the compound?

Determine the empirical and molecular formulas of each 
of the following substances: 
(c) Epinephrine (adrenaline), a hormone secreted into the 
bloodstream in times of danger or stress, contains 59.0% 
C, 7.1% H, 26.2% O, and 7.7% N by mass; its molar mass 
is about 180 u.

If yellow spheres represent sulfur atoms and red spheres represent oxygen atoms, which of the following drawings shows a collection of sulfur dioxide (SO2) units?
(a) <img src="" alt="" />
(b) <img src="" alt="" />
(c) <img src="" alt="" />
(d) <img src="" alt="" />

From the given molar mass and empirical formula of several 
compounds, find the molecular formula of each compound. 
c. C3H2N, 312.29 g/mol

Each of the pictures (a)–(d) represents one of the following substances at 25 °C: sodium, chlorine, iodine, sodium chloride. Which picture corresponds to which substance?
(a) <img src="https://lightcat-files.s3.amazonaws.com/problem_images/f34de37d8e83445d-1668613181822.jpg" alt="" />

What is the molecular formula of each of the following 
compounds? 
(a) empirical formula CH3O, molar mass 5 62.0 g/mol

From the given empirical formula and molar mass, find the
molecular formula of each compound.
a. C6H7N, 186.24 g/mol

The structural formula of isopropyl alcohol, better known as “rubbing alcohol,” is shown. What is the chemical for-mula of isopropyl alcohol?

Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order.
(a) Alanine (an amino acid)

The molecular weight of an organic compound was found by mass spectrometry to be 70.042 11. Is the sample C5H10, C4H6O, or C3H6N2? Exact masses of elements are: 1.007 825 (1H); 12.000 00 (12C); 14.003 074 (14N); 15.994 915 (16O).

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1. Intro to General Chemistry

2. Atoms & Elements

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

7. Gases

8. Thermochemistry

9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Empirical Formula

The empirical formula gives the relative number of atoms.&nbsp;

Percent Yield

The Percent Yield determines how successful the product yield is in a chemical reaction.&nbsp;

The&nbsp;molecular formula gives the actual number of atoms.

Naming Ionic Compounds

An ionic compound is composed of a positive ion and a negative ion.&nbsp;

Functional Groups in Chemistry

The Functional Group is the portion of a molecule that is responsible for its chemical reactivity.&nbsp;

Naming Molecular Compounds

Molecular Compounds, also known as covalent compounds, contain only non-metals bonded together.&nbsp;

Naming Ionic Hydrates

An Ionic Hydrate is an ionic compound that is linked to at least one molecule of H2O.&nbsp;

Stoichiometry

Stoichiometry deals with the numerical relationship between compounds in a balanced chemical equation.

Writing Ionic Compounds

Determining the charges of a cation and anion are fundamental in Writing Ionic Compounds.

Polyatomic Ions

Polyatomic Ions are groups of multiple elements that possess a charge.

Balancing Chemical Equations

Balancing Chemical Equations is the first step in future chemical calculations.

Limiting Reagent

The Limiting Reagent represents the compound that is totally consumed in the reaction.&nbsp;

Combustion Analysis

Under Combustion Analysis, the empirical formula of a compound is determined through a combustion reaction.&nbsp;

Mass Percent

Mass Percent is the percentage of a particular element within a compound.&nbsp;

Combustion Apparatus

A Combustion Apparatus vaporizes a sample into gases to later determine its formula.

Naming Acids

Acids, for the most part, are covalent compounds that begin with a hydrogen.&nbsp;