2. Atoms & Elements

Calculating Molar Mass

How To Calculate Molecular Weight and Molar Mass!

The units for molar mass are in grams per mole.&nbsp;

 This is the simple average of the isotopes.  The abundance must also be considered. 

 This is the simple average of the isotopes.  The abundance must also be considered.   More than two significant figures are justified. 

 The atomic mass of an element represents the weighted average of the isotopic masses. 

Use the data in the table to calculate the atomic mass of silicon. <table><caption>Exact Mass and Abundance of 3 Isotopes of Silicon</caption><tbody><tr><th scope="col">Isotope</th><th scope="col">Isotopic Mass</th><th scope="col">Abundance</th></tr><tr><th scope="row">28Si</th><td>27.97693 amu</td><td>92.23%</td></tr><tr><th scope="row">29Si</th><td>28.97649 amu</td><td>4.67%</td></tr><tr><th scope="row">30Si</th><td>29.97376 amu</td><td>3.10%</td></tr></tbody></table>

If 6.02 * 1023 atoms of element Y have a mass of 83.80 g, what is the identity of Y?

The ball-and-stick molecular model is a representation of caf-feine. Calculate the molecular weight of caffeine. (Gray = C, red = O, blue = N, ivory = H.) (LO 3.3) <img src="https://lightcat-files.s3.amazonaws.com/problem_images/3ff7842c7c428044-1668089232712.jpg" alt="" />
(a) 194.2
(b) 182.2
(c) 192.2
(d) 180.2

What are the molecular weights of the following herbicides? 
(c) C8H6Cl2O3 (dicamba, effective on broadleaf plants

The molecular formula of salicylic acid, a compound commonly
found in facial cleanser, is C7H6O3. (a) What is the molar
mass of salicylic acid?

(d) What is the molar mass of cholesterol if 0.00105 mol has 
a mass of 0.406 g?

Determine the formula weights of each of the following
compounds: (e) iron pyrite, FeS2,
which has a golden appearance and is known as “Fool’s Gold.”

What are the molecular weights of the following herbicides? 
(a) C6H6Cl2O3 (2, 4-dichlorophenoxyacetic acid, effective on broadleaf plants)

One method to synthesize ionic solids is by the heating of
two reactants at high temperatures. Consider the reaction
of FeO with TiO2 to form FeTiO3. Determine the amount of
each of the two reactants to prepare 2.500 g FeTiO3, assuming
the reaction goes to completion.
(b) Calculate the formula weight of FeTiO3.

What is the molecular weight of chloroform if 0.0275 mol weighs 3.28 g?

Calculate the molecular weight of C3H5N3O3.

Suppose that on another planet the atmosphere consists of 17% Kr, 38% CH4, and 45% O2. What is the average molar mass at the surface? What is the average molar mass at an altitude at which all the O2 is photodissociated?

3.3 &#215; 10&#8211;2 moles Ag

 Correct, this quantity has a larger mass and contains more atoms of Ag than the other choices. 

 All of the above represent the same amount of Ag. 

 Convert all quantities to the same units and then compare. 

 Which of the following represents the largest amount of Ag? 

Calculating Molar Mass - Clutch Prep Chemistry

What are the molecular weights of the following pharmaceuticals? 
(b) C22H27F3O4S (fluticasone, anti-inflammatory)

What are the molecular (formula) weights of the following substances? 
(b) C4H8O2 (butyric acid, responsible for the odor of rancid butter)

What is the molecular weight of cholesterol if 0.5731 mol weighs 221.6 g?

What are the molecular weights of the following pharmaceuticals? 
(a) C33H35FN2O5 (atorvastatin, lowers blood cholesterol)

What are the molecular (formula) weights of the following substances? 
(c) CF2Cl2 (a chlorofluorocarbon that destroys the stratospheric ozone layer

Match the descriptions (a)–(e) with the following terms: atomic weight, atomic mass, mass number, atomic number, molar mass.
(a) The mass of a specific atom such as one atom of 13C 
(b) The quantity determined by the number of protons in an element.
(c) The number of grams in 1 mol of an element 
(d) The number of protons and neutrons in an element 
(e) The weighted average of the isotopic masses of an element’s naturally occurring isotopes

 The atomic mass is very close the mass of the heaviest isotope which must provide the largest contribution to the weighted average mass.  

 Correct, the weighted average atomic mass is closest to the mass of this isotope. 

The atomic mass of argon is 39.948 amu. Without any mathematical computations, which of the following isotopes has the largest natural abundance?  <table><caption>Exact Mass 3 Isotopes of Argon</caption><tbody><tr><th scope="col">Isotope</th><th scope="col">Isotopic Mass</th></tr><tr><th scope="row">36Ar</th><td>35.96755 amu</td></tr><tr><th scope="row">38Ar</th><td>37.96272 amu</td></tr><tr><th scope="row">40Ar</th><td>39.96238 amu</td></tr></tbody></table>

The molecular weight of a compound is the sum of the atomic masses of all atoms in the molecule. What is the molecular mass of acetaminophen (C8H9NO2), the active ingredient in Tylenol?

Calculating Molar Mass Example 1

Calculate the formula mass for each compound.
c. C6H12O6

Calculating Molecular Formulas Step by Step | How to Pass Chemistry

What are the molecular weights of the following herbicides? 
(b) C15H22ClNO2 (metolachlor, pre-emergent herbicide)

Chemistry Lesson: Molar Mass

A 67.2 g sample of a gold and palladium alloy contains
2.49 * 1023 atoms. What is the composition (by mass) of the
alloy?

Calculate the formula mass for each compound.
a. MgBr2

The reaction between nickel metal and hydrochloric acid is not a simple dissolution. The product formed is NiCl2 • 6 H2O (s), nickel (II) chloride hexahydrate, which has exactly 6 waters of hydration in the crystal lattice for every nickel ion. What is the molar mass of nickel (II) chloride hexahydrate, NiCl2 • 6 H2O (s)?

Cytochrome c is an iron-containing enzyme found in the cells of all aerobic organisms. If cytochrome c is 0.43% Fe by mass, what is its minimum molecular weight?

What are the molecular weights of the following pharmaceuticals? 
(c) C16H16ClNO2S (clopidogrel, inhibits blood clots)

How to Calculate Molar Mass

What are the molecular (formula) weights of the following substances? 
(a) Hg2Cl2 (calomel, used at one time as a bowel purgative)

(d) What is the molar mass of diazepam (Valium®) if 0.05570 
mol has a mass of 15.86 g?

How to Calculate Molar Mass (Molecular Weight)

What is the molar mass of diazepam also known as Valium if 0.05570 mol weighs 15.86 g?

The molecular formula of saccharin, an artificial sweetener, is 
C7H5NO3S. (a) What is the molar mass of saccharin?

How to Calculate Molar Mass Step by Step with Examples & Practice Problems

Molar Mass Calculations

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1. Intro to General Chemistry

3. Chemical Reactions

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

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Millikan Oil Drop Experiment

The Oil Drop Experiment helped with determining the fundamental charge of the electron.&nbsp;

Ions

Ions represent elements that possess either a positive charge or a negative charge.&nbsp;

Periodic Table: Charges

Elements lose or gain electrons to have the ideal number of outer shell electrons like the noble gases.&nbsp;

Law of Definite Proportions

"Different samples of a pure chemical compound always contain the same proportions of elements by mass."

Periodic Table: Classifications

The Periodic Table contains 3 Major Classifications when describing its elements

Isotopes

Isotopes are atoms of an element that have the same atomic number, but different mass number.&nbsp;

The Atom

The atom represents the basic functional unit in chemistry

Mole Concept

The Mole Concept involves the interconversions between different unit amounts of a substance.

Periodic Table: Representative Elements & Transition Metals

The Groups of the Periodic Table can be broken down into the Representative Elements and Transition Metals

Atomic Theory

John Dalton, one of the "Fathers of Chemistry"is credited with modernizing the Atomic Theory.

Subatomic Particles

The atom is composed of 3 subatomic particles:neutrons, protons, and electrons.

Periodic Table: Elemental Forms

The elements of the Periodic Table exist in different elemental forms in the natural world

Periodic Table: Phases

Under standard conditions of temperature and pressure, the elements can exist as solids, liquids or gases

Atomic Mass

The atomic mass of an element includes the masses of all 3 subatomic particles of neutrons, protons and electrons.&nbsp;

Periodic Table: Group Names

The Periodic Table can be further classified into Periods and Groups.&nbsp;

Law of Conservation of Mass

"In a chemical reaction, no matter is created or destroyed, but instead changes form."

Molar Mass is a physical property that represents the mass of a substance divided by the amount of that substance.

Rutherford Gold Foil Experiment

The Gold Foil Experiment helped with the discovery of the positively charged nucleus.

Law of Multiple Proportions

“When 2 elements (A &amp; B) form different compounds, the mass of Element B that combine with 1 g of A are a ratio of whole numbers."

Periodic Table: Element Symbols

The Element Symbols of the Periodic Table represent the abbreviated form of an element