AP Chemistry Chapter 2 Quiz

1. Which of the following are incorrectly paired?

K, alkali metal

Ba, alkaline earth metal

O, halogen

Ne, noble gas

Ni, transition metal

The incorrect pairing in the given options is O, halogen. Oxygen (O) is not a halogen, but rather a nonmetal. Halogens are a group of elements that include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Explanation

The incorrect pairing in the given options is O, halogen. Oxygen (O) is not a halogen, but rather a nonmetal. Halogens are a group of elements that include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

2. All of the following are true except:

Ions are formed by adding electrons to a neutral atom.

Ions are formed by changing the number of protons in an atom’s nucleus.

Ions are formed by removing electrons from a neutral atom.

An ion has a positive or negative charge.

Metals tend to form positive ions.

Ions are formed by adding or removing electrons from a neutral atom, not by changing the number of protons in an atom's nucleus. Changing the number of protons would result in a different element altogether, not an ion.

Explanation

Ions are formed by adding or removing electrons from a neutral atom, not by changing the number of protons in an atom's nucleus. Changing the number of protons would result in a different element altogether, not an ion.

3. The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

75 protons, 75 neutrons.

75 protons, 130 neutrons.

130 protons, 75 neutrons.

75 protons, 110 neutrons.

Not enough information is given.

The element rhenium (Re) has an atomic number of 75, which corresponds to the number of protons in its nucleus. The atomic number determines the element's identity. The isotope mentioned, rhenium-185, has 110 neutrons in its nucleus. This can be calculated by subtracting the atomic number (75) from the mass number (185). Therefore, the correct answer is 75 protons, 110 neutrons.

Explanation

The element rhenium (Re) has an atomic number of 75, which corresponds to the number of protons in its nucleus. The atomic number determines the element's identity. The isotope mentioned, rhenium-185, has 110 neutrons in its nucleus. This can be calculated by subtracting the atomic number (75) from the mass number (185). Therefore, the correct answer is 75 protons, 110 neutrons.

4. Which one of the following statements about atomic structure is false?

An atom is mostly empty space.

Almost all of the mass of the atom is concentrated in the nucleus.

The protons and neutrons in the nucleus are very tightly packed.

The number of protons and neutrons is always the same in the neutral atom.

All of the statements given are true.

The statement "The number of protons and neutrons is always the same in the neutral atom" is false because the number of neutrons can vary in an atom. The number of protons determines the atomic number and defines the element, while the number of neutrons can vary, resulting in different isotopes of the same element.

Explanation

The statement "The number of protons and neutrons is always the same in the neutral atom" is false because the number of neutrons can vary in an atom. The number of protons determines the atomic number and defines the element, while the number of neutrons can vary, resulting in different isotopes of the same element.

5. Which of the following is incorrectly named?

Pb(NO3)2, lead (II) nitrate

NH4ClO4, ammonium perchlorate

PO4 3-, phosphate ion

Mg(OH)2, magnesium hydroxide

NO3 -, nitrite ion

The given answer, NO3 -, nitrite ion, is incorrectly named. The correct name for NO3 - is nitrate ion, not nitrite ion. Nitrite ion is represented as NO2 -.

Explanation

The given answer, NO3 -, nitrite ion, is incorrectly named. The correct name for NO3 - is nitrate ion, not nitrite ion. Nitrite ion is represented as NO2 -.

6. In a combustion reaction, 46.0g of ethanol reacts with 96.0g of oxygen to produce water and carbon dioxide. If 54.0g of water is produced, what mass of carbon dioxide is produced? Use proper sig figs. (hint: law of conservation of mass)

In a combustion reaction, ethanol reacts with oxygen to produce water and carbon dioxide. The balanced equation for this reaction is: C2H5OH + 3O2 → 2CO2 + 3H2O. According to the stoichiometry of the equation, for every 2 moles of CO2 produced, 3 moles of H2O are produced. Therefore, the ratio of the masses of CO2 to H2O produced is 2:3. Given that 54.0g of water is produced, we can use this ratio to calculate the mass of CO2 produced. (54.0g water) * (2g CO2 / 3g H2O) = 36.0g CO2. However, since we are asked to use proper sig figs, the answer should be rounded to three significant figures, which gives us 36.0g CO2.

Explanation

In a combustion reaction, ethanol reacts with oxygen to produce water and carbon dioxide. The balanced equation for this reaction is: C2H5OH + 3O2 → 2CO2 + 3H2O. According to the stoichiometry of the equation, for every 2 moles of CO2 produced, 3 moles of H2O are produced. Therefore, the ratio of the masses of CO2 to H2O produced is 2:3. Given that 54.0g of water is produced, we can use this ratio to calculate the mass of CO2 produced. (54.0g water) * (2g CO2 / 3g H2O) = 36.0g CO2. However, since we are asked to use proper sig figs, the answer should be rounded to three significant figures, which gives us 36.0g CO2.

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7. Which of the following statements from Dalton's atomic theory is no longer true, according to modern atomic theory?

Elements are made up of tiny particles called atoms.

Atoms are not created or destroyed in chemical reactions.

All atoms of a given element are identical.

Atoms are indivisible in chemical reactions.

All of these statements are true according to modern atomic theory.

According to modern atomic theory, the statement "All atoms of a given element are identical" from Dalton's atomic theory is no longer true. Modern atomic theory recognizes that atoms of the same element can have different isotopes, which means they can have different numbers of neutrons. This variation in the number of neutrons leads to differences in atomic mass, but the atoms still have the same number of protons and electrons, maintaining their elemental identity.

Explanation

According to modern atomic theory, the statement "All atoms of a given element are identical" from Dalton's atomic theory is no longer true. Modern atomic theory recognizes that atoms of the same element can have different isotopes, which means they can have different numbers of neutrons. This variation in the number of neutrons leads to differences in atomic mass, but the atoms still have the same number of protons and electrons, maintaining their elemental identity.

8. Write the names of the following compounds in order: (hint: use all lower case letters and capitals in parenthesis for roman numerals)

FeSO₄
NaC₂H₃O₂
KNO₂
Ca(OH)₂
NiCO₃

The given compounds are listed in order according to their names. The names of the compounds are written using all lower case letters and capital letters in parenthesis for the roman numerals. The compounds are: iron (II) sulfate, sodium acetate, potassium nitrite, calcium hydroxide, and nickel (II) carbonate.

Explanation

The given compounds are listed in order according to their names. The names of the compounds are written using all lower case letters and capital letters in parenthesis for the roman numerals. The compounds are: iron (II) sulfate, sodium acetate, potassium nitrite, calcium hydroxide, and nickel (II) carbonate.

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9. Identify the periodic groups associated with Alkali metals, Alkaline earth metals, Halogens, Noble gases and transition metals, in order. (use group numbers 1 through 18 and a series of groups with a dash, ex: 1-3)

The periodic groups associated with the given elements in order are group 1 (alkali metals), group 2 (alkaline earth metals), group 17 (halogens), group 18 (noble gases), and groups 3-12 (transition metals).

Explanation

The periodic groups associated with the given elements in order are group 1 (alkali metals), group 2 (alkaline earth metals), group 17 (halogens), group 18 (noble gases), and groups 3-12 (transition metals).

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10. Write the chemical formulas for the following compounds or ions, in order. Place subscripts, parenthesis, and charges where they are needed. Do not 'lower' the subscripts and leave a space between the ion and its charge. example: phosphate ion= PO4 3-, copper (II) nitrate = Cu(NO3)2, chloride ion = Cl -

nitrate ion
aluminum oxide
ammonium ion
perchloric acid
copper (II) bromide

The chemical formulas for the given compounds or ions are as follows: nitrate ion (NO3 -), aluminum oxide (Al2O3), ammonium ion (NH4 +), perchloric acid (HClO4), copper (II) bromide (CuBr2).

Explanation

The chemical formulas for the given compounds or ions are as follows: nitrate ion (NO3 -), aluminum oxide (Al2O3), ammonium ion (NH4 +), perchloric acid (HClO4), copper (II) bromide (CuBr2).

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