Chapter 8

Molar Mass

100

True or false:

The molar mass of an element is the same number in grams as the mass number of the element's heaviest isotope.

False

200

Which is heaviest, one mole of Calcium, Zirconium, or Aluminum?

Zirconium

300

Which contains more atoms, one mole of Calcium, Zirconium, or Aluminum?

All are the same

400

Which contains more oxygen atoms?

40 g of CaO

40 g MnO₂

40 g O₂

40 g O₂

500

To three significant figures, what is the molar mass of Na₂SO₄?

142 g

How Many Moles

100

How many moles of atoms is 38 g of fluorine?

2.0

200

Which contains more moles of atoms?

24 g of oxygen molecules

48 g of sulfur atoms

48 g of sulfur atoms

300

If you have 5.5 x 10²⁴ bromine molecules, how many bromine atoms do you have?

1.1 x 10²⁵ bromine atoms

400

2 moles of ammonium carbonate contains how many moles of ammonium ions?

4 moles

500

How many dollars is Avogadro's number of nickels?

$3.01 x 10²²

How Many Grams

100

What is the mass of 2.6 mole of tin?

310 g

200

What is the mass of 2.6 mole of sulfur dioxide?

170 g

300

What  is the mass of 3.01 x 10²³ oxygen atoms?

8.00 g

400

Which of the following have the same mass?

3.0 x 10²³ argon atoms

3.0 x 10²³ sodium hydroxide units

3.0 x 10²³ potassium hydroxide units

3.0 x 10²³ calcium atoms

argon, calcium, and sodium hydroxide are the same

500

What is the mass of 1.0 x 10²⁴ lead(II) oxide particles?

370 g PbO

Percent Composition

100

A compound composed of potassium, chromium, and oxygen contains 26.6% K, 35.4% Cr.  What is the percent O?

38.0% O

200

10.0 g of water was tested and found to contain 88.8% oxygen.  If the test is repeated with 17.2 g of water, what would be the % oxygen?

88.8% oxygen

300

What is % Na in NaCl?

39.3% Na

400

25 g of Fe₂O₃ is used to make iron metal.  How much Fe can be produced?

17 g Fe

500

Given equal masses of the following three copper minerals, which would produce the most copper?

Chalcocite:  Cu₂S

Villamaninite: CuS₂

Covellite: CuS

Chalcocite

Empirical Formula

100

Which of the following must be an empirical formula?

K₂Cr₂O₄

(NH₄)₂S₂O₈

ZrO(NO₃)₂

C₃H₆O₃

ZrO(NO₃)₂

200

True or false:

The molecular formula of a compound is always the same as its empirilcal formula

False

300

A compound is 15.8 % carbon and 84.2% sulfur.  What is its empirical formula?

CS₂

400

A compound has a molar mass of 87 g and an empirical formula of OCl₂.  What is its molecular formula?

OCl₂

500

A compound is 40% calcium, 12% carbon, and 48% oxygen.  What is its empirical formula?

CaCO₃