Answers to Self Quiz

List of atomic weights:

N = 14.0 O = 16.0 S = 32.1 Cl = 35.5 Cr = 52.0

1. What is the formula weight (molecular weight) for NO₂?

46.0 g/mole

2. A compound has the molecular formula N₂O₄. What is its empirical formula?

NO₂

3. Write the formula for a molecule which has two nitrogen atoms and five oxygen atoms.

N₂O₅

4. A compound contains .328 g Cr and .672 g Cl. What is its empirical formula?

CrCl₃

5. A compound with an empirical formula of CH₂ has a molecular weight of 56. What is its molecular formula?

C₄H₈

6. What is the relationship between a mole of an element and the atomic weight of the element?

The atomic weight of an element is the weight in grams of one mole of that element.

7. How many moles are there in 8.00 g of SO₂?

0.125 moles

8. Calculate the percent composition by weight of SO₂.

50.1 % sulfur and 49.9 % oxygen

9. What is the weight in grams of 0.60 moles of S?

19 g

10. State the basic points of Dalton's theory.

Elements consist of very small, indivisible particles called atoms. All atoms of a given element are identical and have a characteristic mass. Atoms of different elements are different from one another. Compounds are made from atoms of different elements adhering to one another. Chemical reactions involve the rearrangement of atoms.

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