Question 1

6.02 10²³g of hydrogen is one mole of hydrogen.

Accepted Answer

The answer of 6.02 10²³g of hydrogen is...

Question 2

C₁₂H₂₂O₁₁ is an empirical formula.

Accepted Answer

The given string of characters is not a valid empirical formula as it does not follow the rules of empirical formula representation. It should have subscripts for each element indicating its ratio in the compound.

Question 3

One mole of glucose,C₆H₁₂O₆,contains 24 moles of atoms.

Accepted Answer

A molecule of glucose (C6H12O6) contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms, totaling 24 atoms. Therefore, one mole of glucose contains 24 moles of atoms.

Question 4

One mole of magnesium and one mole of magnesium sulfate contain the same number of magnesium atoms.

Accepted Answer

One mole of any element contains the same number of atoms (Avogadro's number, approximately 6.02 x 10^23) regardless of the compound it is part of. Therefore, one mole of magnesium and one mole of magnesium sulfate contain the same number of magnesium atoms.

Question 5

Two moles of O₃ contain the same number of oxygen atoms as three moles of O₂.

Accepted Answer

The subscripts indicate the number of atoms for each element in the compound. Therefore, two moles of O₃ contain 2 x 1 oxygen atoms = 2 oxygen atoms, while three moles of O₂ contain 3 x 1 oxygen atoms = 3 oxygen atoms. Since two equals three, the statement is true.

Question 6

The compounds FeO and Fe₂O₃ have the same empirical formula.

Accepted Answer

FeO has an empirical formula of FeO, indicating a 1:1 ratio of iron to oxygen, while FeS has an empirical formula of FeS, indicating a 1:1 ratio of iron to sulfur. The presence of different elements (oxygen vs. sulfur) means they cannot have the same empirical formula.

Question 7

A compound with the empirical formula CH₂O can have a molar mass of 150.15g.

Accepted Answer

The empirical formula CH₂O represents a compound with a molar mass of 30.03 g/mol. The given molar mass of 150.15 g/mol is five times the empirical formula mass, indicating a molecular formula of C₅H₁₀O₅.

Question 8

O₃ is an empirical formula.

Accepted Answer

O₃ is not an empirical formula because empirical formulas consist of chemical symbols followed by subscripts indicating the proportion of atoms in the simplest ratio, and this sequence does not follow those conventions.

Question 9

One mole of oxygen has a mass of 8.00g.

Accepted Answer

One mole of oxygen (O2) has a mass of approximately 32.00g, based on the atomic mass of oxygen being about 16.00g/mol and the molecule being O2.

Question 10

A 2.489 sample of a compound is found to contain water.When heated,the water is driven off.The mass of the remaining compound is 1.591g.
A.What is the mass of the water that was lost?
B.What is the percent by mass of the water in the original compound?

Accepted Answer

The answer of A 2.489 sample of a compound is...

Question 11

If you analyze two unknown substances and find that they have the same empirical formula, then these two unknown substances are the same.

Accepted Answer

Two substances can have the same empirical formula but different molecular formulas. Thus, they can have different chemical and physical properties.

Question 12

A mole contains Avogadro's number of particles.

Accepted Answer

A mole is defined as the amount of substance that contains the same number of particles (atoms, molecules, or other entities) as there are in 12 grams of pure carbon-12, which is Avogadro's number (6.02 x 10^23). Therefore, a mole contains Avogadro's number of particles.

Question 13

The compounds C₂H₂ and C₆H₆ have the same percent composition by mass.

Accepted Answer

Since the compounds have the same percent composition by mass, it means that the ratio of the masses of each element in the compounds is the same. Thus, the subscripts (or number of atoms) for each element in each compound must also be the same. Therefore, both compounds have the same subscripts for each element, and thus have the same chemical formula.

Question 14

A sample of glucose,C₆H₁₂O₆,has a mass of 300.0g. A.What mass of carbon atoms is in the sample? B.What mass of hydrogen atoms is in the sample? C.What mass of oxygen atoms is in the sample?

Accepted Answer

The answer of A sample of glucose,C₆H₁₂O₆,has a mass of...

Question 15

A sample of glucose,C₆H₁₂O₆,has a mass of 300.0g. A.How many moles of carbon atoms are in the sample? B.How many moles of hydrogen atoms are in the sample? C.How many moles of oxygen atoms are in the sample?

Accepted Answer

The answer of A sample of glucose,C₆H₁₂O₆,has a mass of...

Question 16

Which of the following contains the greatest number of atoms?

Accepted Answer

Lithium has the smallest molar mass among the given elements, meaning a given mass (1.0g) of lithium will contain more moles, and consequently, more atoms than the same mass of sodium, aluminum, or silver.

Question 17

Which of the following contains the largest number of moles?

Accepted Answer

Lithium has the smallest molar mass among the given options, which means 1.0g of lithium will contain more moles than 1.0g of any of the other elements listed.

Question 18

A 3.000g sample of a compound is found to contain water.When heated the water is driven off.The mass of the remaining compound is 1.465g.
A.What is the mass of the water that was lost?
B.What is the percent by mass of the water in the original compound?

Accepted Answer

The answer of A 3.000g sample of a compound is...

Question 19

All of the following contain the same number of molecules except

Accepted Answer

Option D, 32.0g of oxygen molecules, contains Avogadro's number of oxygen molecules (6.02 x 10²³) which is the same as the number of molecules in option A, 1.20 x 10²⁴ molecules of water. Option B and option C have different molecular weights and therefore a different number of molecules.

Question 20

One mole of magnesium has the same number of atoms but a smaller mass than one mole of sulfur.

Accepted Answer

One mole of any substance contains Avogadro's number of particles, which is 6.022 x 10^23. Therefore, one mole of magnesium and one mole of sulfur both contain the same number of atoms. However, the mass of one mole of magnesium (24.31 g) is smaller than the mass of one mole of sulfur (32.06 g) due to the difference in atomic mass between the elements.

Quiz 7: Quantitative Composition of Compounds

6.02 1023 g of hydrogen is one mole of hydrogen.

C12H22O11 is an empirical formula.

One mole of glucose,C6H12O6,contains 24 moles of atoms.

One mole of magnesium and one mole of magnesium sulfate contain the same number of magnesium atoms.

Two moles of O3 contain the same number of oxygen atoms as three moles of O2.

The compounds FeO and Fe2O3 have the same empirical formula.

A compound with the empirical formula CH2O can have a molar mass of 150.15g.

O3 is an empirical formula.