Mole Unit and Average Atomic Mass Quiz

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Questions and Answers

What is the average atomic mass of a carbon atom?

12.011 amu

The atomic mass unit is based on the ______atom.

carbon-12

How many amu are in 1 gram?

6.02 x 10^23 amu

The average atomic mass of an element is typically a whole number.

False Signup and view all the answers

What is the average atomic mass of boron?

10.81 amu Signup and view all the answers

The average atomic mass of an element is determined by taking into account the ______ of each stable isotope.

abundance Signup and view all the answers

What is the average atomic mass of the unknown element in Practice Packet #1?

14.0067 amu Signup and view all the answers

What is the unknown element in Practice Packet #1?

nitrogen Signup and view all the answers

What is the average atomic mass of the new theoretical element in Practice Packet #2?

271.94 amu Signup and view all the answers

How many grams are in 1 amu?

1.66 x 10^-24 g Signup and view all the answers

If one atom of hydrogen has a mass of 1.0 amu, how many hydrogen atoms are required to make 1.0 g of hydrogen?

6.02 x 10^23 hydrogen atoms Signup and view all the answers

A mole is a unit of measurement that represents a specific number of particles.

True Signup and view all the answers

A mole is equivalent to ______ particles.

6.02 x 10^23 Signup and view all the answers

What is the mass of a single carbon-12 atom in grams?

1.99 x 10^-23g Signup and view all the answers

How many carbon-12 atoms are there in a sample weighing 12.00 g?

6.02 x 10^23 atoms Signup and view all the answers

How many silver atoms are present in 3.00 moles of silver atoms?

1.81 x 10^24 silver atoms Signup and view all the answers

How many molybdenum atoms are present in 10.0 moles of molybdenum atoms?

6.02 x 10^24 molybdenum atoms Signup and view all the answers

How many moles of barium atoms are there in 4.81 x 10^24 barium atoms?

7.99 moles of barium Signup and view all the answers

How many moles of boron atoms are there in 3.75 x 10^24 boron atoms?

6.23 moles of boron Signup and view all the answers

The molar mass of an element is the same as its atomic mass in grams.

True Signup and view all the answers

What is the molar mass of carbon?

12.011 g/mol Signup and view all the answers

What is the molar mass of molybdenum?

92.94 g/mol Signup and view all the answers

The molar mass of an element is the mass of one ______ of that element.

mole Signup and view all the answers

The mass of one ______ of carbon is 12.011 grams.

mole Signup and view all the answers

One atom of carbon has a mass of ______ amu.

12.011 Signup and view all the answers

One mole of carbon atoms has a mass of ______ grams.

12.011 Signup and view all the answers

What is the mass of 5.00 moles of tungsten?

919 g Signup and view all the answers

What is the molar mass of silver?

107.9 g/mol Signup and view all the answers

What is the molar mass of permanganic acid (HMnO4)?

119.9 g/mol Signup and view all the answers

What is the molar mass of potassium oxalate (K2C2O4)?

166.2 g/mol Signup and view all the answers

What is the molar mass of tetranitrogen decoxide (N4O10)?

216.0 g/mol Signup and view all the answers

What is the molar mass of octene (C8H16)?

112.2 g/mol Signup and view all the answers

The mass of one molecule of octene is ______ amu.

112.2 Signup and view all the answers

The mass of one mole of octene is ______ grams.

112.2 Signup and view all the answers

What is the mass of 2.00 moles of octene?

224 g Signup and view all the answers

What is the mass of 4.00 moles of calcium?

160 g Signup and view all the answers

What is the mass of 1.24 moles of lead?

257 g Signup and view all the answers

What is the mass of 0.00750 moles of potassium oxalate?

1.25 g Signup and view all the answers

What is the mass of 22.2 moles of tetranitrogen decoxide?

4790 g Signup and view all the answers

How many moles of gold atoms are present in 39.4 grams of gold?

0.200 moles Signup and view all the answers

How many moles of sodium atoms are present in 321 grams of sodium?

14.0 moles Signup and view all the answers

One mole of permanganic acid has a mass of ______ grams.

119.9 Signup and view all the answers

How many moles of permanganic acid (HMnO4) are present in 1199 grams of the compound?

10.0 moles Signup and view all the answers

How many moles of cobalt are present in a 16.0 gram sample?

0.274 moles Signup and view all the answers

How many moles of zinc are present in a 111 gram sample?

1.69 moles Signup and view all the answers

How many moles of platinum are present in a 2.84 gram sample?

0.0145 moles Signup and view all the answers

How many moles of octene (C8H16) are present in a 311 gram sample?

2.77 moles Signup and view all the answers

How many moles of potassium oxalate (K2C2O4) are present in a 5.33 gram sample?

0.0321 moles Signup and view all the answers

How many carbon atoms are present in a 4.80 gram sample of carbon?

2.41 x 10^23 atoms Signup and view all the answers

How many cobalt atoms are present in 16.0 grams of cobalt?

1.65 x 10^23 atoms Signup and view all the answers

How many zinc atoms are present in 111 grams of zinc?

1.02 x 10^24 atoms Signup and view all the answers

How many platinum atoms are present in 2.84 grams of platinum?

8.70 x 10^21 atoms Signup and view all the answers

How many molecules of tetranitrogen decoxide (N4O10) are present in a 82.4 gram sample?

2.77 x 10^23 molecules Signup and view all the answers

How many atoms are present in a 82.4 gram sample of tetranitrogen decoxide (N4O10)?

1.66 x 10^24 atoms Signup and view all the answers

How many grams of permanganic acid (HMnO4) are present in a sample containing 4.19 x 10^22 molecules?

11.2 g Signup and view all the answers

How many calcium atoms are present in a 20.0 gram sample of calcium?

3.01 x 10^23 atoms Signup and view all the answers

What is the mass in grams of 3.83 x 10^25 lithium atoms?

255 g Signup and view all the answers

What is the mass in grams of 8.173 x 10^22 potassium oxalate molecules?

21.6 g Signup and view all the answers

What is the volume in liters of a spherical ball of iron with a density of 7.874 g/mL and a radius of 47.0 mm?

0.207 L Signup and view all the answers

What is the percent by mass of hydrogen in water (H2O)?

11.2% Signup and view all the answers

What is the percent by mass of hydrogen in carbonic acid (H2CO3)?

3.20% Signup and view all the answers

What is the percent by mass of carbon in carbonic acid (H2CO3)?

19.4% Signup and view all the answers

What is the percent by mass of carbon in carbon dioxide (CO2)?

27.3% Signup and view all the answers

What is the percent by mass of carbon in butane (C4H10)?

82.7% Signup and view all the answers

What is the percent by mass of hydrogen in butane (C4H10)?

17.3% Signup and view all the answers

What is the percent by mass of hydrogen in dichromic acid (H2Cr2O7)?

1.70% Signup and view all the answers

What is the percent by mass of chromium in dichromic acid (H2Cr2O7)?

35.3% Signup and view all the answers

What is the percent by mass of oxygen in dichromic acid (H2Cr2O7)?

63.0% Signup and view all the answers

What is the percent by mass of arsenic in arsenic triiodide (AsI3)?

19.8% Signup and view all the answers

What is the percent by mass of iodine in arsenic triiodide (AsI3)?

80.2% Signup and view all the answers

What is the percent by mass of antimony in antimony(V) phosphite (Sb3(PO3)5)?

33.1% Signup and view all the answers

What is the percent by mass of phosphorus in antimony(V) phosphite (Sb3(PO3)5)?

14.4% Signup and view all the answers

What is the percent by mass of oxygen in antimony(V) phosphite (Sb3(PO3)5)?

52.5% Signup and view all the answers

What is the empirical formula of butane (C4H10)?

C2H5 Signup and view all the answers

What is the empirical formula of a compound that is 30.44% nitrogen and 69.56% oxygen?

NO2 Signup and view all the answers

What is the empirical formula of a compound that is 84.12% carbon and 15.88% hydrogen?

C4H9 Signup and view all the answers

What is the empirical formula of a compound that is 80.0% carbon and 20.0% hydrogen?

CH3 Signup and view all the answers

What is the empirical formula of a compound that is 27.29% carbon and 72.71% oxygen?

CO2 Signup and view all the answers

What is the empirical formula of a compound that is 25.94% nitrogen and 74.06% oxygen?

N2O5 Signup and view all the answers

What is the empirical formula of a compound that is 3.25% hydrogen, 19.36% carbon, and 77.39% oxygen?

H2CO3 Signup and view all the answers

What is the empirical formula of a compound composed of 20.19% magnesium, 26.64% sulfur, and 53.17% oxygen?

MgSO4 Signup and view all the answers

What is the empirical formula of a compound that has the molecular formula C6H6?

CH Signup and view all the answers

What is the empirical formula of a compound that has the molecular formula X39Y13?

X3Y Signup and view all the answers

What is the molecular formula of a compound that has an empirical formula of N2O5 and a molar mass of 216.0 g/mol?

N4O10 Signup and view all the answers

What is the molecular formula of a compound that has an empirical formula of C2H4O and a molar mass of 132.0 g/mol?

C6H12O3 Signup and view all the answers

What is the molecular formula of a compound that has an empirical formula of CBrOF and a molar mass of 254.7 g/mol?

C2Br2O2F2 Signup and view all the answers

What is the empirical formula of a nitrogen and oxygen compound that contains 36.84% nitrogen?

N2O3 Signup and view all the answers

What is the molecular formula of a nitrogen and oxygen compound that has an empirical formula of N2O3 and a molar mass of approximately 228 g/mol?

N6O9 Signup and view all the answers

Study Notes

Mole Unit (Compound Calculations)

The mole is a unit used to count atoms, molecules, ions, etc.
The mole is roughly equal to the Avogadro's number.
Avogadro's number is 6.02 x 10²³.
1 amu = 1.66 x 10^-24 g

Average Atomic Mass

Average atomic mass takes into account the abundance of each stable isotope.
Isotopes are atoms of the same element with different numbers of neutrons.
Calculate the average atomic mass by taking the mass of each isotope and multiplying it by its percentage abundance, and then sum the products.
- Example: Boron has two stable isotopes, B-10 and B-11. B-10 has a mass of 10.01 amu and makes up 19.9% of all stable boron atoms. B-11 has a mass of 11.01 amu and makes up 80.1% of all stable boron atoms.

Practice Problems

Packet #1: Calculate average atomic mass of an unknown element with two isotopes: isotope 1 (mass = 14.003074 amu and abundance = 99.63%); isotope 2 (mass = 15.000108 amu).
Packet #2: Calculate the average atomic mass of a hypothetical element with three isotopes. Data for isotopes (mass and % abundance) are included in the presentation.
Packet #10 (Tungsten): Calculate atomic mass and molar mass of tungsten in amu and grams
Packet #13: Calculate the percent abundance of an isotope X-243, given the mass of isotope X-240 (240.240 amu), isotope X-243 (243.534 amu) and the average atomic mass (241.800 amu).
Packet #15 (Gold): Calculate the number of moles of gold atoms given 39.4 grams of gold, knowing that 1 mole of gold has a mass of 197.0 g.

The Mole (Part 2)

A mole represents a specific number of particles, atoms, or molecules.
A mole of a substance, has a mass in grams equal to its atomic mass, or molecular mass.

More About the Mole

A mole of any substance contains Avogadro's number of particles
Calculate the number of atoms in 10 moles of Mo, knowing that a mole of any element contains Avogadro's number of atoms

Practice Problems continued

Packet #6: Calculate the number of Ag atoms in 3.00 moles of Ag atoms
Packet #7: Calculate the number of Mo atoms in 10.0 moles of Mo
Packet #8: Calculate the number of moles of Ba atoms given 4.81 x 10²⁴ atoms of Ba
Packet #9: Calculate the number of moles of B atoms given 3.75 x 10²⁴ atoms of B

Two Aspects of the Mole

A mole is a number of particles (atoms, molecules, etc.).
A mole is a specific mass of an element or compound, measured in grams, equal to its atomic mass or molecular mass.

Practice Problems Continued

Packet #10 (Carbon): Calculate the mass of one atom of carbon, and the mass of a mole of carbon atoms.
Packet #10 (Moles of different elements and compounds): Calculate the masses of various samples of elements and compounds in grams
Packet #12 (Moles of different elements and compounds): Calculate the molar mass of specified elements and compounds.
- The data for elements from the periodic table is used for relevant calculations.

Empirical Formula

The empirical formula represents the simplest whole-number ratio of atoms in a compound.
Steps for determining the empirical formula: convert mass percents of elements to their individual masses using a assumed 100-g sample, find the number of moles of each element to determine the ratio, and simplify to the lowest whole number ratio.

Molecular Formula

The molecular formula is the actual formula of a molecule, showing the exact number of each type of atom.
Determine the molecular formula from the empirical formula and molar mass by determining the factor the molecular formula is off from the empirical molar mass, and multiplying the empirical formula by that factor.

Hydrates

Hydrates are ionic compounds containing water molecules within their crystalline structure.
The prefix system for hydrates: Use prefixes to indicate the number of water molecules. (EX. 1-mono, 2-di, 3-tri, 4-tetra, 5-penta, 6-hexa, 7-hepta)
Steps to analyze a hydrate: Determine the mass of each compound within the hydrate (ionic compound, water), find the number of moles by converting the masses to moles, Simplify by dividing the ratio of moles by the smaller number of moles.