**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 10 ^{22}**
molecules of

**Answer: 5.39 g N _{2}**

**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, O_{2}**

**Answer: 1.21 x 10 ^{22} molecules O_{2}**

**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 HC _{2}H_{3}O_{2}**

**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: C _{2}H_{4}O_{1}**

**Sample Problems in the text: p
248-249 #47-56**

**Optional Paper & Pencil:
Homework 2.5 points **