Unit 3 Stoichiometry Practice Quiz: Empirical and Molecular Formulas

An educational illustration featuring a molecular structure with chemical formulas and symbols, showcasing elements such as carbon, hydrogen, and oxygen with a background of a periodic table.

Stoichiometry Challenge: Empirical and Molecular Formulas Quiz

Test your knowledge of stoichiometry and discover how well you understand empirical and molecular formulas with our engaging quiz! This quiz is designed to challenge students and enthusiasts alike, providing a variety of questions that cover key concepts in chemistry.

Key Features:

Multiple-choice questions covering essential topics.
Ideal for students and anyone interested in chemistry.
Learn and improve your understanding of chemical formulas.

10 Questions2 MinutesCreated by CalculatingChemist27

1.) In mass spectrometry, organic compounds are deliberately fragmented in order to deduce their molecular structure. One fragment containing only carbon and hydrogen has 14.3% H. Which of the following is the fragment in question?

(A) CH

(B) CH4

(D) CH2

2.) A substance has an empirical formula of CH2. It's molar mass is determined in a separate experiment as 83.5. What is the most probable molecular formula for this compound.

(A) C2H4 because it is simplest formula after CH2

(B) C6H12 because it is the hydrocarbon with a molar mass close to the experimental molar mass

(D) C4H3O2 because this has a molar mass closest to 83.5

3.) A 0.200-g sample of a compound containing only carbon, hydrogen and oxygen is burned, and 0.357g of CO2 and 0.146g of H2O are collected. What is the percentage of carbon in the original compound and what can that value be used for?

(A) 56.0% and this can be used to obtain the empirical formula

(B) 73.0% and this can be used to name the compound

(D) 24.3% and this can be used to track CO2 in the atmosphere.

4.) Determine the empirical formula for a compound that is 25% hydrogen and 75% carbon. Is this likely to be the molecular formula

(A) CH. No, this cannot be the molecular formula because carbon forms 4 bonds.

(B) CH2. Yes, this can be the molecular formula because carbon often forms 2 bonds.

(D) C2H8. No, this cannot be the molecular formula since carbon atoms have more than 4 bonds in this formula.

6.) A compound is found to contain 26.56% potassium, 35.41% chromium, and the remainder oxygen. Find its empirical formula.

(A) K2Cr2O7

(B) KCrO4

(D) KCrO2

7.) A 60.00 g sample of tetraethyllead, a gasoline additive, is found to contain 38.43 g lead, 17.83 g carbon, and 3.74 g hydrogen. Find its empirical formula

(A) PbC6H12

(B) PbC10H22

(C)PbC8H20

(D) Pb2C6H12

8.) A 170.00 g sample of an unidentified compound contains 29.84 g sodium, 67.49 g chromium, and 72.67 g oxygen. Find the empirical formula.

(A) Na2CrO4

(B) NaCrO4

(D) Na2Cr2O7

9.) Determine the molecular formula of the compound with an empirical formula of CH and a formula mass of 78.110 u.

(A) C6H12

(B) C6H6

(D) C5H8

10.) Determine the molecular formula of a compound with an empirical formula of NH2 and a formula mass of 32.06 u.

(A) N2H4

(B) N3H6

(D) N5H10

Unit 3 Stoichiometry Practice Quiz: Empirical and Molecular Formulas

Stoichiometry Challenge: Empirical and Molecular Formulas Quiz

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