All AP Chemistry Resources
Example Questions
Example Question #27 : Elemental Composition Of Pure Substances
Name the following compound:
Zinc chlorate
Zinc chloride
Zinc dichlorate
Zinc chloride tetroxide
Zinc perchlorate
Zinc perchlorate
The compound's name is zinc perchlorate. With the addition of a fourth oxygen atom to the molecule, chlorate , we follow the polyatomic ion naming rules and add a per- to the molecule's name, giving us perchlorate. When bonded ionically to a zinc cation , the resulting ionic compound is called zinc perchlorate.
Example Question #31 : Elemental Composition Of Pure Substances
What is the formula of hydroiodic acid?
is the correct formula because, following IUPAC acid naming rules, when combining a hydrogen cation with an anion that consists of only one element (in this case iodide), one drops the -ide ending, adds an -ic ending and adds a hydro- prefix. Other examples would be hydrochloric acid and hydrofluoric acid .
Example Question #771 : Ap Chemistry
A student named a certain organic molecule 2-(1-methylbutyl)-3-isopropylbutane. While this name may give the possibility of correctly drawing the molecule, it does not follow correct IUPAC naming guidelines. What is the correct name of this molecule?
2-pentyl-3-propylbutane
3,4-dimethyl-2-isopropylheptane
2-(2-pentyl)-3-isopropylbutane
3-(2-pentyl)-2-isopropylbutane
2,3,4,5-tetramethyloctane
2,3,4,5-tetramethyloctane
While the student's description of the location and size of the sidechains is correct, he/she failed to recognize the longest parent chain, it being the eight-carbon string which encompasses what he/she named isopropyl- and pentyl-. The resulting octane molecule has four methyl- substituents at the 2, 3, 4, and 5 positions.
Example Question #33 : Elemental Composition Of Pure Substances
Which of the molecules above does not match its molecular formula?
Isobutane
Decane
Pentane
Nonane
Butane
Butane
While it is tempting to think that butane and isobutane, because of their structural differences would have different numbers of of hydrogens, they are in fact constitutional isomers, and have the same molecular formula. Both butane and isobutane have four carbons and ten hydrogens, although butane's carbons and hydrogen's are arranged
and isobutane's are arranged
A good rule of thumb for the formulas of simple hydrocarbons is:
Example Question #772 : Ap Chemistry
Which of the following is a correct name for the compound, ?
I: Potassium bicarbonate
II: Potassium percabonate
III: Potassium hydrogen carbonate
III only
I only
I and III
II only
II and III
I and III
Because the ion, , is correctly referred to as both bicarbonate and hydrogen carbonate, the correct names for the compound in question are both potassium bicarbonate and potassium hydrogen carbonate.
Example Question #35 : Elemental Composition Of Pure Substances
Which of these is not the IUPAC name for the indicated molecule?
Acetic acid;
Carbonous acid;
Hydrofluoric acid;
Perchlorous acid;
Sulfuric acid;
Perchlorous acid;
Because the polyatomic ion from which the acid, , is derived is perchlorate, , the resulting acid is named perchloric acid. The naming protocol is to use the -ic suffix for acids derived from polyatomic ions ending in -ate, while using the -ous suffix for acids derived from polyatomic ions ending in -ite.
Example Question #773 : Ap Chemistry
What is the name of the compound with the chemical formula ?
Dinitrogen monoxide
Hyponitrite
Nitrite
Nitrate
Pernitrate
Dinitrogen monoxide
All of the incorrect options have prefixes or suffixes associated with polyatomic ions "hypo," "per," "ite," and "ate". Since is not an ion (it does not have a charge), it must just be a covalent compound. Therefore, use the prefixes reserved for covalent compounds to name it.
Example Question #774 : Ap Chemistry
What is the name of the compound with the chemical formula: ?
Iron monoxide
Iron (II) oxide
Iron (I) oxide
Iron oxide
Iron (III) oxide
Iron (II) oxide
The name of this compound is iron (II) oxide. First, notice how the chemical formula contains one metal and one nonmetal, so we know that we are not going to be using prefixes such as "mono" because those are used for covalent compounds. Secondly, notice that iron is a transition metal, which means that we have to specify the charge it has, in roman numerals. Iron must have a positive two charge to balance out the negative two charge oxygen will have.
Example Question #775 : Ap Chemistry
Name of the following compound:
Magnesium(II) aresenate
Magnesium(II) perarsenate
Magnesium arsenate
Magnesium perarsenate
Magnesium arsenite
Magnesium arsenate
This is an ionic compound, we know that because we see a metal bound to a nonmetal. To name ionic compounds, first write the name of the metal, or cation: magnesium. Next, we have the polyatomic ion arsenate . Thus our answer is: magnesium arsenate. Since magnesium is not a transition metal, we do not need to indicate its charge with Roman numerals. If arsenate was part of a series of oxyanions (anions that contain oxygen), we use the prefix "per" to indicate more oxygens, however this is not the case.
Example Question #776 : Ap Chemistry
What is the name of the following compound?
Iron trihydroxide
Iron (II) hydroxide
Ferrous hydroxide
Iron (III) hydroxide
Iron (III) hydroxide
To name this compound, it's important to first notice what the formal charge would be on each of the constituent ions. We know that the formal charge of a hydroxide ion is . Since there are three of these, and because we know the compound is neutral, the iron constituent must have a charge of . Therefore, this compound is correctly called iron (III) hydroxide.
It's also important to note that there are alternate names for iron (II) and iron (III). Iron (II) is sometimes referred to as "ferrous" while iron (III) is sometimes referred to as "ferric." An easy way to remember this is to note that "ferrous" has an "O" in it and so does the word "lower" (lower as in the lower charge of the +2 iron). Moreover, the term "ferric" has an "I" in it and so does the word "higher" (higher as in the higher charge of +3 iron).
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