Page 391 - Teacher Preview Copy

Constructed Response . Topic 6: Moles and Stoichiometry

Set A: Moles of atoms in formulas.

Write your answers here.

1. What is the total number of moles of oxygen atoms 1.

in 1 mole of the formula MgSO4.7H2O

2. What is the total number of moles of hydrogen in 2 moles 2.

of the formula NH4HCO3 ?

3. What is the total number of moles of atoms in 0.5 moles 3.

of the formula Al2(CO3)3?

Teacher Preview Copy

Set B. Gram formula ( molar ) mass calculation, mole calculation, empirical formula

Base your answers to questions 4 through 6 on the formula of a compound below.
C4H10O8
Write your answers here.

4. Calculate the formula mass of the compound. 4.

Your work should include the correct numerical
set up.

5. Calculate the number of moles in 17.7 grams of 5.

the compound. Teacher Preview Copy

6. What is the empirical formula for this compound 6.

Set C: Gram formula mass calculation, percent composition of water in hydrates

Base your answers to questions 7 through 9 on the information below.

Gypsum is a mineral that is used in the construction industry to make drywall

(sheetrock). The chemical formula for this hydrated compound is CaSO4 .2H2O.

A hydrated compound contains water molecules within the crystalline structures.

Gypsum contains 2 moles of water for each 1 mole of calcium sulfate.

7.What is the gram-formula mass of CaSO4 . 2 H2O. 7.

8. Show a correct numerical setup for calculating the 8.

percent composition by mass of water in this

compound and record your result.

9. What is the IUPAC name for gypsum, CaSO4. 2H2O 9.
Copyright©2010 E3 Scholastic Publishing. All Rights Reserved. SurvivingChem.com 381