CHM 2045C Module Five Sample Exam

Part B: Mole calculation (Sections 2.5)       4 points

Calculate the mass in grams of 1.16 x 1022 molecules of nitrogen gas, N2

Answer: 5.39 g N2

Sample Problems in Kotz6e text: p 91 Problems #27-34

Optional Homework: 2.5 points paper and pencil

 

Calculate the number of molecules in 0.641 g of oxygen gas, O2

Answer: 1.21 x 10 22 molecules O2

Sample Problems in Kotz6e text: p 91 Problems #27-34

Optional Homework: 2.5 points paper and pencil

 

Part C: Percent Composition (section 3.6)         3 points

Calculate the percent composition of each element in the following compound:

Online: http://people.emich.edu/bramsay1/ccc-release/chem.html

Answers: 6.71% Hydrogen; 40.00% Carbon; 53.28% Oxygen

Acetic Acid    HC2H3O2

Sample Problems in the Kotz6e text: p 134 #41-46

Optional Paper & Pencil: Homework 2.5 points

 

Part D: Empirical Formula Calculation (Section 4.6)           4 points

Given the following percent compositions, determine the empirical formula of the following compound: 54.5% carbon, 9.15% hydrogen, and 36.3% oxygen

Answer: C2H4O1

Sample Problems in the Kotz6e text: p 134-135  #47-56

Optional Paper & Pencil: Homework 2.5 points