Library Guides: Chemistry Textbook: Self-Assessments

1. Matter and MeasurementsToggle Dropdown
2. Atoms, Molecules and Ions
3. Composition of Substances and SolutionsToggle Dropdown
4. Stoichiometry of Chemical ReactionsToggle Dropdown
5. ThermochemistryToggle Dropdown
6. GasesToggle Dropdown
7. Chemical Bonding and Molecular GeometryToggle Dropdown
8. Liquids, Solids, and Modern MaterialsToggle Dropdown
9. Solutions and Colligative PropertiesToggle Dropdown
10. KineticsToggle Dropdown
11. Chemical Equilibria and ApplicationsToggle Dropdown
12. ThermodynamicsToggle Dropdown
13. ElectrochemistryToggle Dropdown
14. AppendicesToggle Dropdown

Self-Assessments

Isotope Symbol
Average atomic mass
Nomenclature I
Nomenclature II
Nomenclature III - acids included

What are the mass number and atomic number of ⁸⁰Br?

Choose 1 answer

Atomic number (Z) = 45; Mass number (A) = 80

Atomic number (Z) = 80; Mass number (A) = 35

Atomic number (Z) = 45; Mass number (A) = 79.9

Atomic number (Z) = 35; Mass number (A) = 80

Atomic number (Z) = 35; Mass number (A) = 45

The number "45" is the number of neutrons in the element. Atomic number should be the number of protons. Review topic here

Atomic number is usually less than the mass number! Review topic here

Mass number refers to the total number of protons and neutrons in the nucleus of an atom; it should be a whole number. 79.9 is not a whole number! Review topic here

Atomic number is the number of protons in an element. In the periodic table, the atomic number is located above the element; atomic number is 35 for bromine which suggests that bromine has 35 protons.
Mass number refers to the total number of protons and neutrons in the nucleus of an atom. The symbol, ⁸⁰Br suggests that the mass number is 80. The ⁸⁰Br isotope (also written as Bromine-80) has a total of 80 protons and neutrons in the nucleus.
Review topic here

Mass number is not correct! Mass number refers to the total number of protons and neutrons in the nucleus of an atom. Review topic here

Iodine-131 isotope is used in diagnosis and treatment of thyroid function.
How many electrons, protons and neutrons are in the ¹³¹I isotope?

Choose 1 answer

53 electrons, 53 protons, 131 neutrons

53 electrons, 53 protons, 78 neutrons

53 electrons, 78 protons and 53 neutrons

53 electrons, 53 protons, 74 neutrons

54 electrons, 53 protons, 78 neutrons

Number of neutrons is not correct! Note that the mass number, 131, represents the number of protons + neutrons. Review topic here

Great job! Atomic number of iodine is 53 as shown on the periodic table. Therefore, the isotope has 53 protons. Review topic here
Because there is no charge, number of electrons is also equal to 53.
Number of neutrons = mass number – protons = 131-53 = 78. Review topic here

Because the given isotope is neutral, number of electrons should be equal to number of protons. Also, the number of neutrons are not determined correctly.
Note that the mass number, 131, represents the number of protons + neutrons.
Review topic here

It looks like you are using 127 as the mass number of the isotope! The mass number of ¹³¹I is 131, which represents the number of protons + neutrons. Review topic here

Because the given isotope is neutral, number of electrons should be equal to number of protons. Review topic here

There are electrons, protons, and ___ neutrons in ¹¹⁰Cd²⁺?

Choose 1 answer

46, 48, 62

48, 50, 62

46, 48, 110

48, 50, 110

50, 48, 62

Cadmium is the 48^th element on the periodic table; it’s atomic number is 48 suggesting that it has 48 protons.
A +2 charge suggests that two electrons are removed. Therefore, number of electrons = 46. (NOTE: The charge of the ion is always due to excess or deficiency of electrons. A deficiency of electrons compared to protons leads to a positive charge because electrons are negative! An excess of electrons leads to a negative charge)
Number of neutrons = mass number – protons = 110-48 = 62.
Review topic here.

An element, whether neutral or with a charge, is identified by the number of protons.
The charge is always a result of excess or deficiency of electrons, not protons!
Review topic here.

Number of neutrons is not correct! Note that the mass number, 110, is the number of protons + neutrons. Review topic here.

p;.gjhkl.All the three are not correct! Note that an element, whether neutral or with a charge, is identified by the number of protons (or atomic number). Review topic here.

Because electrons are negative, removing them leads to a positive charge! Review topic here.

What is the symbol of the isotope with 92 electrons, 92 protons and 145 neutrons?

Choose 1 answer

⁹²Pm

⁹²Np

¹⁴⁵U

²³⁸U

²³⁷U

The element symbol is not Pm! Note that an element is identified by it’s number of protons. Review topic here.

The element symbol is not Np! Note that an element is identified by it’s number of protons. Review topic here.

The element is identified correctly. However, you seem to have used number of protons in the place of mass number! Review topic here.

The element is identified correctly, however, the mass number is not mass number is not 238! Mass number is the number of protons and neutrons in the nucleus of an atom. Review topic here.

The element is identified by the number of protons. There are 92 protons in Uranium, hence the atomic symbol is U.
Mass number = protons + neutrons = 33+46 = 79.
Review topic here.

What is the symbol of the isotope with 35 electrons, 33 protons and 46 neutrons?

Choose 1 answer

⁷⁹Br^2-

⁸¹Br²⁺

⁷⁹As^2-

⁷⁹As²⁺

⁸¹As

You may have used number of electrons to determine the element’s identity. The element is not Bromine! Review topic here.

Element symbol, charge and mass number are not correct. Review topic here

An element is identified by the number of protons. Arsenic (As) is the element with 33 protons. 33 protons and 35 electrons leads to a net charge of -2.
Mass number = protons + neutrons = 33+46 = 79.
Review topic here.

Net charge should be the sum of charges from 35 electrons and 35 protons. Review topic here.

The element should have a charge as the number of electrons and protons are not the same! Also, the mass number is not correct. Review topic here.

Weapons-grade uranium is enriched with over 90% of Uranium-235 isotope which can undergo nuclear fission.
A sample of enriched uranium contains 95.430% ²³⁵U (235.0439 amu) and the rest is the naturally occurring ²³⁸U (238.0508 amu). What is the average atomic mass of the enriched uranium?

Choose 1 answer

235.02 amu

235.13 amu

235.18 amu

235.35 amu

236.50 amu

About 95% of the mass came from ²³⁵U whose mass is 235.0439 amu. Since the rest is coming from an isotope with a higher mass, the average atomic mass should be greater than 235.0439 amu.
Average atomic mass refers to the weighted atomic mass of an element.
Weighted average atomic mass is the sum of (fractional abundance × mass of the isotope) for all isotopes.

Looks like you used the 235 amu and 238 amu as the masses of the isotopes while calculating the weighted average. You must use the exact masses, 235.0439 amu and 238.0508 amu.

Weighted average atomic mass is the sum of (fractional abundance × mass of the isotope) for all isotopes.

The percent abundance of ²³⁸U in the sample = 100-95.430 = 4.570%.
Fractional abundance of ²³⁵U = 95.430/100 = 0.95430; fractional abundance of ²³⁸U 4.570/100 = 0.04570.
Weighted average atomic mass = (0.95430 × 0439 amu) + (0.04570 × 238.0508 amu) = 235.18 amu.

Average atomic mass refers to the weighted atomic mass of an element.
Weighted average atomic mass is the sum of (fractional abundance × mass of the isotope) for all isotopes.

Looks like you have calculated a simple average. Average atomic mass refers to the weighted atomic mass of an element. The percent contribution from each isotope must be taken into consideration.

A naturally occurring sample of an element-X contains three isotopes with the following natural abundances.
67% ⁷⁵X (mass: 75.121 amu)
53.02% ⁷⁶X⁽mass: 75.812 amu)
1.310% ⁷⁷X (mass: 77.112) amu

Choose 1 answer

75.12 amu

75.51 amu

75.60 amu

76.02 amu

76.82 amu

Weighted average atomic mass is the sum of (fractional abundance × mass of the isotope) for all isotopes.

Weighted average atomic mass is the sum of (fractional abundance × mass of the isotope) for all isotopes. Fractional abundance of ⁷⁵X is 45.67/100= 0.4567; fractional abundance of ⁷⁶X is 0.5302; fractional abundance of ⁷⁷X = 0.0131.

Weighted average atomic mass = (0.4567 × 75.121 amu) + (0.5302 ×812amu) + (0.0131 × 77.112 amu) = 235.18 amu.

Weighted average atomic mass is the sum of (fractional abundance × mass of the isotope) for all isotopes.

Looks like you calculated a simple average and not a weighted average! The percent contributions from each isotope must be considered.

Most of the sample is made of ¹⁴⁵X and ¹⁴⁶ The average atomic mass cannot be close to 77 amu!

Which isotope is most abundant isotope of Magnesium?

Choose 1 answer

Magnesium-26

Magnesium-27

Magnesium-24

Magnesium-23

All of them are equally abundant

You will need the periodic table to determine this.

Answer based on the average atomic mass of Magnesium.

From the periodic table, we know that the average atomic mass of Magnesium is 24.31 amu. As the average mass is closer to Magnesium-24, it is likely that Magensium-24 contributes most to the average mass, hence, is the most abundant isotope.

You will need the periodic table to determine this.

Naturally occurring elements usually contain one isotope in a greater abundance than the rest.

Boron has two isotopes, ¹⁰B of mass 10.013 amu and ¹¹B of mass 11.009 amu. What is the natural abundance of ¹⁰B isotope?

Choose 1 answer

10%

20%

30%

60%

80%

Hint: fractional abundances add to 1. View similar example 2.4.

Average atomic mass = Σ (fractional abundance × mass of isotope).
The average atomic mass from the periodic table = 10.811 amu; Let fractional abundance of ¹⁰B be x; the fractional abundance of ¹¹B will be 1-x as fractional abundances must add up to 1.

811 amu = [(x)(10.013 amu) + (1-x)(11.009 amu)]
x = 0.1987; Percent abundance of ¹⁰B= 0.1987 × 100 = 19.87%

The average atomic mass of Boron can be obtained from the periodic table. Assume that the fractional abundance of ¹⁰B is x, the natural abundance of ¹¹B is 1-x.
View similar example 2.4.

Hint: fractional abundances add to 1. The average atomic mass of Boron can be obtained from the periodic table.
View similar example 2.4.

Hint: fractional abundances add to 1. Substitute in the formula for average atomic mass.
View similar example 2.4.

Magnesium has three natural isotopes, Magnesium-24, Magnesium-25 and Magnesium-26 of masses 23.985042 amu, 24.985837 amu and 25.982593 amu, respectively. The natural abundance of Magnesium-24 is 78.99%. What is the natural abundance of Magnesium-25?

Choose 1 answer

79.0%

81.4%

10.0%

6.29%

4.12%

The percent abundances of ²⁵Mg and ²⁶Mg should add up to (100-78.99) %

View solution here.

The percent abundances of ²⁵Mg and ²⁶Mg should add up to (100-78.99) %

Which of the following substances is a molecular compound?

Choose 1 answer

V₂O₅

N₂O₅

K₃P

FeCl₃

LiOH

V₂O₅ contains metal (vanadium) and non-metal (oxygen). Metals want to lose electrons and form positive ions and non-metals want to gain electrons and form negative ions. The positive and negative ions attract by what are known as ionic bonds and the compound is said to be an ionic compound. Therefore, V₂O₅ is an ionic compound.

Since Nitrogen and Oxygen are both non-metals, N₂O₅ is a molecular compound.

A molecular compound is a substance with discrete molecules where in the atoms are bonded by covalent bonds (i.e. by sharing electrons). Usually, non-metals bond to each other by sharing electrons as there is not a significant difference in their abilities to lose/gain electrons. Therefore, compounds containing two non-metals will be molecular compounds.

Potassium is a metal and phosphorus is a non-metal. K₃P is an ionic compound. It contains potassium that has lost electrons (K⁺) and phosphorus that has gained electrons (P^3-) and the ions attract each other by what are known as ionic bonds.

Iron is a metal and chlorine is a non-metal. Metals want to lose electrons and form positive ions and non-metals want to gain electrons and form negative ions. The positive and negative ions attract by what are known as ionic bonds and the compound is said to be an ionic compound. Therefore, FeCl₃ is an ionic compound.

Lithium is a metal. Metals want to lose electrons and form positive ions (Li⁺). Hydroxide is a negatively charged ion (OH^-). The bonding between Li⁺ and OH^- is ionic bonding. Hence, LiOH is an ionic compound.

Which of the following substances is an ionic compound?

Choose 1 answer

HCl

PCl₃

C₂H₅OH

Al₂S₃

SeBr₂

Hydrogen and chlorine are both non-metals. Hydrogen and chlorine bond by sharing electrons, hence, HCl is a molecular compound.

Phosphorus and chlorine are both non-metals. Phosphorus and chlorine bond by sharing electrons, hence, PCl₃is a molecular compound.

C, H and O are all non-metals. They bond to each other by sharing electrons, hence, C₂H₅OH is a molecular compound.
Note: C₂H₅OH is commonly known as ethanol.

Aluminum is a metal and sulfur is a non-metal. The metal and non-metal from ions (Al³⁺, S^2- ions) that bond together by ionic bonding. Therefore, Al₂S₃ is an ionic compound.

Selenium and bromine are both non-metals. They both bond by sharing electrons, hence, SeBr₂is a molecular compound.

Which of the following is the correct name of AlBr₃ according to the Nomenclature conventions?

Choose 1 answer

Aluminum bromide

Aluminum tribromide

Aluminum(III) bromide

Aluminum bromite

Aluminum bromate.

Good job! AlBr₃is an ionic compound, so, naming it involves stating the cation name followed by the anion name (Br^- is bromide). A roman numeral is not needed to specify the charge of aluminum, because aluminum which is in group 3A (or group 13) can only from one stable ion with a +3 charge.

Sorry! AlBr₃ is an ionic compound. The prefixes mono, di, tri, etc. are used when naming molecular compounds!

A roman numeral is not needed to specify the charge of aluminum, because aluminum which is in group 3A (or group 13) can only from one stable ion with a +3 charge.

The anion in AlBr₃ is Br^-, which is a monoatomic The name of Br^- ion is bromide, not bromite!

The anion in AlBr₃ is Br^-, which is a monoatomic The name of Br^- ion is bromide, not bromate!

Which of the following formula-name pair is NOT correct?

Choose 1 answer

LiOH: Lithium hydroxide

Rb₂SO₄: Rubidium sulfate

FeCl₃: Iron chloride

NaCH₃COO: Sodium acetate

NH₄I: ammonium iodide

Type of compound: LiOH is an ionic compound.
Check formula: Lithium is in group#1, so lithium ion is Li⁺. The polyatomic anion is hydroxide (OH^-). One Lithium ion (+1 total charge) and one hydroxide ion (-1 total charge) lead to a net charge of zero. So, the formula of the compound is correct.
Check name: An ionic compound should be named with cation name followed by anion name. The name lithium hydroxide is correct.

Type of compound: Rb₂SO₄ is an ionic compound.
Check formula: Rubidium is in group#1, so Rubidium ion is Rb⁺. The polyatomic anion is sulfate (SO₄^2-). Two Rubidium ions (+2 total charge) and one sulfate ion (-2 total charge) lead to a net charge of zero. So, the formula of the compound is correct.
Check name: An ionic compound should be named with cation name followed by anion name. Hence, the name Rubidium sulfate is correct.

The name is not correct because roman numeral is needed while naming a transition metal ion.
Analyze:
Type of compound: FeCl₃ is an ionic compound.
Check formula: Iron is a transition metal. The monoatomic ion is chloride (Cl^-). Iron must have a charge of +3 to balance the charge from three chloride ions (Cl^-) in the compound.
Check name: An ionic compound should be named with cation name followed by anion name. The name of the transition metal ion, Fe³⁺, is iron(III); the roman numeral in the parenthesis signifies the charge . Hence, the name of FeCl₃ should be iron(III) chloride.

Type of compound: NaCH₃COO is an ionic compound.
Check formula: sodium is in group#1, so lithium ion is Na⁺. The polyatomic anion is acetate (CH₃COO^- or C₂H₃O₂^-). One sodium ion (+1 total charge) and one acetate ion (-1 total charge) lead to a net charge of zero. So, the formula of the compound is correct.
Check name: An ionic compound should be named with cation name followed by anion name. Hence, the name sodium acetate is correct.
Note: sometimes, the formula is also written as CH₃

Type of compound: NH₄I is an ionic compound. (Note: Compounds that contain NH₄⁺ ions are ionic compound because there are positive and negative ions, even though the cation is not a metal).
Check formula: The polyatomic cation is ammonium (NH₄⁺). The anion is a monoatomic iodide ion; since iodine is in group 7A (or group 17), it’s formula is I^-. One ammonium ion and one iodide ion lead to a net charge of zero. So, the formula of the compound is correct.
Check name: An ionic compound should be named with cation name followed by anion name. The name ammonium iodide is correct.

Which of the following formula-name pair is NOT correct?

Choose 1 answer

K₂O: potassium oxide

Ca₃N₂: calcium nitride

VF₅: Vanadium(V) fluoride

BrCl: bromine chloride

MgSe: Magnesium selenide

K₂O is an ionic compound containing two potassium ions (K⁺) and one oxide (O^2-) ion. It’s name, potassium oxide, is correct.

Ca₃N₂ is an ionic compound containing three calcium ions (Ca²⁺) and two nitride (N^3-) ions. It’s name, calcium nitride, is correct.

VF₅ is an ionic compound containing one Vanadium(V) ion (V⁵⁺) and five fluoride (F^-) ions. It’s name, Vanadium(V) fluoride, is correct.

The name of the compound is Bromine monochloride.
BrCl is a molecular compound. It does not contain ions! Molecular compounds are named using prefixes such as mono, di, tri to specify the number atoms. The prefix, “mono” is dropped at the beginning of the compound name.

MgSe is an ionic compound containing one Magnesium ion (Mg²⁺) and one selenide ion (Se^2-). Ionic compounds are named with the cation name followed by anion name. Hence, the name Magnesium selenide is correct.

Which of the following compounds is NOT named correctly?

Choose 1 answer

Ca(NO₃)₂: calcium nitrate

Co₂SO₄: Cobalt(II) sulfate

K₂CO₃: potassium carbonate

CuCl: Copper(I) chloride

(NH₄)₂S: ammonium sulfide

Ca(NO₃)₂ is an ionic compound containing one Ca²⁺ and two NO₃^- The cation is calcium ion and the anion name is nitrate. Hence, calcium nitrate is the correct name.

The charge of cobalt ion is not correct in the formula.
Co₂SO₄ is an ionic compound containing a transition metal; charge of the metal ion must be specified in parenthesis when naming. There are two cobalt ions and one SO₄^2- (sulfate) ion in the compound. To balance the total positive and negative charge, each cobalt ion has +1 charge. Hence, the compound name should be cobalt(I) sulfate.

K₂CO₃ is an ionic compound containing two K⁺ ions and one CO₃^2- The cation is potassium ion and the anion name is carbonate. Hence, potassium carbonate is the correct name.

CuCl is an ionic compound containing a transition metal; charge of the metal ion must be specified in parenthesis when naming. There is one copper ion and one Cl^- (chloride) ion in the compound. To balance the positive and negative charge. the copper ion has a +1 charge. Hence, the compound name Copper(I) chloride is correct.

(NH₄)₂S is an ionic compound containing two NH₄⁺ and one sulfide ion S^2-. The cation name is ammonium, and the anion name is sulfide. Hence, the name ammonium sulfide is correct.

Which of the following compound’s formula is correct?

Choose 1 answer

Barium hydroxide: BaOH₂

Strontium nitrite: Sr₃N₂

Ammonium phosphate: (NH₄)₂PO₄

Dichlorine heptoxide: Cl₂O₆

Magnesium chlorate: Mg(ClO₃)₂

Barium hydroxide is Ba(OH)₂.

Nitrite is a polyatomic ion (NO₂^-). Strontium nitrite is Sr(NO₂)₂.

Ammonium phosphate is (NH₄)₃PO₄.

Dichlorine heptoxide is Cl₂O₇.

Magnesium ion is Mg²⁺. Chlorate is ClO₃^-. Hence, the magnesium chlorate is Mg(ClO₃)₂. The formula is correct.

Which of the following formula- name pair is NOT correct?

Choose 1 answer

Pd(NO₃)₂: Palladium(II) nitrate

Li₂SO₃: Lithium sulfate

CsI : Cesium iodide

Ni₂CO₃: Nickel(I) carbonate

KOH: potassium hydroxide

NO₃^- is nitrate. There are two nitrates in the compound, so, palladium has a charge of +2. The name, palladium(II) nitrate is correct.

The name Lithium sulfate is not correct.
The name of SO₃^2- is sulfite since there is one oxygen less than sulfate. Hence. Li₂SO₃ should be Lithium sulfite.

CsI is an ionic compound. I^- is iodide. The name of the compound is indeed Cesium Iodide.

CO₃^2- is carbonate. Since there are two Nickel ions in the compounds, each Nickel has a charge of +1 to balance the total positive and negative charge in the compound. The name, nickel(I) carbonate is correct.

OH^- is hydroxide ion. Hence KOH is potassium hydroxide.

What is the name of CrPO₃?

Choose 1 answer

Chromium phosphate

monochromium phosphate

Chromium(I) phosphite

Chromium(III) phosphite

Chromium(III) phosphate

Both cation and anion are not named correctly!

The compound is an ionic compound. Prefixes (such as mono) should not be used when naming ionic compounds.

The charge of chromium is not +1!

Great job! PO₃^3- is phosphite ion (one oxygen less than phosphate). The charge on Chromium should be +3 to balance the positive and negative charge. Hence, the name of the compound is Chromium(III) phosphite.

The anion is not named correctly!

Which of the following compounds is NOT named correctly?

Choose 1 answer

Pb(BrO₃)₂: Lead(II) bromate

Au₂CO₃: Gold(I) carbonate

AlPO₃: Aluminum phosphide

V₂O₅: Vanadium(V) oxide

CS₂: carbon disulfide

For metal cations other than Aluminum, group#1 and group#2 ions, the charge is specified using a roman numeral. So, a roman numeral is needed to specify the charge of the lead (Pb) ion.
BrO₃^- is bromate ion. Since there are two bromate ions in the compound, the charge on lead ion is +2 to balance the total positive and negative charge. Hence, Pb(BrO₃)₂is correctly named lead(II) bromate.

There is a transition metal in the compound, so a roman numeral is needed in the cation name.
CO₃^2- is carbonate. Since there are two gold ions in the compound, the charge on each gold ion is +1 so the total positive charge equals total negative charge. Hence, Au₂CO₃ is correctly named Gold(I) carbonate.

PO₃^3- ion is a polyatomic ion; its name is phosphite since it has one oxygen less than phosphate. AlPO₃ is Aluminum phosphite.

There is a transition metal in the compound, so a roman numeral is needed in the cation name.
The anion is oxide (O^2-) ions. The total negative charge due to five oxide ions is -10. Since there are two vanadium ions, each has a +5 charge to balance the total positive and negative charge. V₂O₅ is correctly named Vanadium(V) oxide.

CS₂ is a molecular compound. Prefixes are needed when naming the compound. Hence, carbon disulfide is the correct name.
Note that the prefix, “mono”, is dropped for carbon because it occurs at the very beginning of the compound name.

What is the formula for chlorous acid?

Choose 1 answer

HCl

HClO₄

HClO₃

HClO₂

HClO

The anion in HCl is chloride (Cl^-). So, the acid name is hydrochloric acid.
Note: If the anion name ends with “ide”, the corresponding acid’s name starts with “hydro” and ends with “ic acid” (ie. hydro _____ ic acid)

The anion in HClO₄ is ClO₄^-. The name of anion is perchlorate (since it has one oxygen more than chlorate). So, the name of the corresponding acid, HClO₄, is perchloric acid.
Note: if the anion is “per___ate” which has one oxygen more than “ate”, the corresponding acid is named “per_____ ic acid”.

The anion in the HClO₃ is ClO₃^-. The name of anion is chlorate. So, the name of the corresponding acid, HClO₃, is chloric acid.
Note: if the anion name ends with “__ate”, the corresponding acid name ends with “___ic acid”.

If the acid name ends with “ous acid”, the corresponding anion name ends with “ite”. So, the corresponding anion of chlorous acid is chlorite, which has one oxygen less than chlorate.
chlorite = ClO₂^-. Hence, chlorous acid = HClO₂.

The anion in HClO is ClO^-. The name of the anion is hypochlorite (since it has two oxygens less than ate). So, the name of the corresponding acid, HClO is hypochlorous acid.
Note: if the anion is “hypo___ite”, which has two oxygens less than “ate”, the corresponding acid is named “hypo____ous acid”.

Which of the following acid name and formula pair is NOT correct?

Choose 1 answer

sulfurous acid: H₂SO₃

phosphoric acid: H₂PO₄

hydroiodic acid: HI

carbonic acid: H₂CO₃

acetic acid: CH₃COOH

The corresponding anion of sulfurous acid is sulfite.
Sulfite has one oxygen less than sulfate but has the same charge as sulfate. Therefore, sulfite is SO₃^2-. Sulfurous acid is H₂SO

The corresponding anion of phosphoric acid is phosphate. The formula of phosphate is PO₄^3-. Hence, phosphoric acid is H₃PO₄, NOT H₂PO₄!

The corresponding anion of hydroiodic acid is iodide (I^-). The formula of hydroiodic acid is HI, indeed!

The corresponding anion of carbonic acid is carbonate (CO₃^2-). So, the formula of carbonic acid is H₂CO₃.

The corresponding anion of acetic acid is acetate (CH₃COO^- or C₂H₃O₂^-). So, the formula of acetic acid is CH₃COOH or HC₂H₃O₂).

What is the name of HIO₄?

Choose 1 answer

hydroiodic acid

iodic acid

periodic acid

hypoiodic acid

iodate

Hint: Identify the name of the anion in HIO₄. Review nomenclature of binary and oxyacids here.

The anion in HIO₄ is IO₄^-. The name of IO₄^- is per-iodate since it has one oxygen more than iodate (IO₃^-). Hence the corresponding acid of periodate should be named periodic acid.
Review more examples of binary and oxyacid nomenclature here.

Hint: Identify the name of the anion in HIO₄. Review nomenclature of binary and oxyacids here.

Sodium hypochlorite is an active ingredient in bleach. What is the formula of sodium hypochlorite?

Choose 1 answer

NaClO₄

Na₂ClO₃

NaClO₂

Na₂ClO

NaClO

Review how many oxygens are less in hypochlorite compared to chlorite.

Hypochlorite ion has two oxygens less than the chlorate ion. Chlorate ion is ClO₃^-; so, hypochlorite is ClO^-. Therefore, sodium hypochlorite is NaClO.

Sodium hydrogen phosphate is used as an anti-caking agent in powdered products. What is the formula of sodium hydrogen phosphate?

Choose 1 answer

Na₃PO₄

NaHPO₄

Na₂HPO₄

NaH₂PO₄

Na₃PO₃

PO₄^3- is a phosphate ion. Hence, Na₃PO₄ is sodium phosphate.

The formula does not use the correct charge on hydrogen phosphate ion.
The formula NaHPO₄ suggests that HPO₄ has a -1 charge! Note that “hydrogen phosphate” ion is the ion that results when one H⁺ is added to phosphate (PO₄^3-).

A “hydrogen phosphate” ion is the ion that results when one H⁺ is added to phosphate (H⁺ + PO₄^3- = HPO₄^2-; note that +1 charge from hydrogen and -3 charge from phosphate add to -2).
Since sodium (Na⁺) is the cation and hydrogen phosphate (HPO₄^2-) is the anion, the formula for sodium hydrogen phosphate after the charges are criss-crossed is Na₂HPO₄.

NaH₂PO₄ is sodium dihydrogen phosphate as it contains sodium ion (Na⁺) and dihydrogen phosphate (H₂PO₄^-) ions.

PO₃^3- is a phosphite ion. Hence, Na₃PO₃ is sodium phosphite.

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Chemistry Textbook

Self-Assessments

What are the mass number and atomic number of 80Br?

Iodine-131 isotope is used in diagnosis and treatment of thyroid function.How many electrons, protons and neutrons are in the 131I isotope?

There are ______ electrons, ______ protons, and _______ neutrons in 110Cd2+?

What is the symbol of the isotope with 92 electrons, 92 protons and 145 neutrons?

What is the symbol of the isotope with 35 electrons, 33 protons and 46 neutrons?

Weapons-grade uranium is enriched with over 90% of Uranium-235 isotope which can undergo nuclear fission.A sample of enriched uranium contains 95.430% 235U (235.0439 amu) and the rest is the naturally occurring 238U (238.0508 amu). What is the average atomic mass of the enriched uranium?

A naturally occurring sample of an element-X contains three isotopes with the following natural abundances. 67% 75X (mass: 75.121 amu)53.02% 76X (mass: 75.812 amu)1.310% 77X (mass: 77.112) amu

Which isotope is most abundant isotope of Magnesium?

Boron has two isotopes, 10B of mass 10.013 amu and 11B of mass 11.009 amu. What is the natural abundance of 10B isotope?

Magnesium has three natural isotopes, Magnesium-24, Magnesium-25 and Magnesium-26 of masses 23.985042 amu, 24.985837 amu and 25.982593 amu, respectively. The natural abundance of Magnesium-24 is 78.99%. What is the natural abundance of Magnesium-25?

Which of the following substances is a molecular compound?

Which of the following substances is an ionic compound?

Which of the following is the correct name of AlBr3 according to the Nomenclature conventions?

Which of the following formula-name pair is NOT correct?

Which of the following formula-name pair is NOT correct?

Which of the following compounds is NOT named correctly?

Which of the following compound’s formula is correct?

Which of the following formula- name pair is NOT correct?

What is the name of CrPO3?

Which of the following compounds is NOT named correctly?

What is the formula for chlorous acid?

Which of the following acid name and formula pair is NOT correct?

What is the name of HIO4?

Sodium hypochlorite is an active ingredient in bleach. What is the formula of sodium hypochlorite?

Sodium hydrogen phosphate is used as an anti-caking agent in powdered products. What is the formula of sodium hydrogen phosphate?

What are the mass number and atomic number of ⁸⁰Br?

Iodine-131 isotope is used in diagnosis and treatment of thyroid function.
How many electrons, protons and neutrons are in the ¹³¹I isotope?

There are electrons, protons, and ___ neutrons in ¹¹⁰Cd²⁺?

Weapons-grade uranium is enriched with over 90% of Uranium-235 isotope which can undergo nuclear fission.
A sample of enriched uranium contains 95.430% ²³⁵U (235.0439 amu) and the rest is the naturally occurring ²³⁸U (238.0508 amu). What is the average atomic mass of the enriched uranium?

A naturally occurring sample of an element-X contains three isotopes with the following natural abundances.
67% ⁷⁵X (mass: 75.121 amu)
53.02% ⁷⁶X⁽mass: 75.812 amu)
1.310% ⁷⁷X (mass: 77.112) amu

Boron has two isotopes, ¹⁰B of mass 10.013 amu and ¹¹B of mass 11.009 amu. What is the natural abundance of ¹⁰B isotope?

Which of the following is the correct name of AlBr₃ according to the Nomenclature conventions?

What is the name of CrPO₃?

What is the name of HIO₄?