CHEM 1001/CHM 1020/ Chm1025C/CHM1032C Name:______________

Module Five SamplePretest

Part B: Mole calculation (Sections 9.2 & 9.4) 5 points

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

Answer: 5.39 g N₂

Sample Problems in text: p 247 17-22

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 text: p 247 5-12

Optional Homework: 2.5 points paper and pencil

Part C: Percent Composition (section 9.7) 5 points

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

Answers:

Acetic Acid HC₂H₃O₂

Sample Problems in the text: p 248 #39-46

Optional Paper & Pencil: Homework 2.5 points

Part D: Empirical Formula Calculation (Section 9.8) 5 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 text: p 248-249 #47-56

Optional Paper & Pencil: Homework 2.5 points