There Are _______ Molecules in 12 Grams of Uf6.

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Chemical Formulas and Composition Stoichiometry Examples of Multiple Choice Questions

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1.

The formula weight of the compound, Al₂(SO₄)₃
18H₂O is:

(a) 394.4 g

(b) 666.4 g

(c) 110,900 g

(d) 466.8 g

(e) 561.2 g

2.

The weight of a millimole of (NH₄)₂HPO₄
is:

(a) 132 g

(b) 114 g

(c) 1.14 x 10^-3
g

(d) 0.132 g

(e) 6.02 x 10²⁰
g

3.

How many moles of alanine, C₃H₇NO₂, are there in 159 g of alanine?

(a) 1.42 x 10⁴

(b) 1.78

(c) 0.992

(d) 0.560

(e) 3.31

4.

How many atoms are in one mole of CH₃OH?

(a) 6

(b) 6.0 x 10²³

(c) 12.0 x 10²³

(d) 3.6 x 10²⁴

(e) 3

5.

The mass in grams of 2.6 x 10²²
chlorine atoms is:

(a) 4.4

(b) 11

(c) 0.76

(d) 1.5

(e) 3.2

6.

How many aluminum atoms are there in 3.50 grams of Al₂O₃?

(a) 4.13 x 10²²

(b) 4.90 x 10²²

(c) 2.07 x 10²²

(d) 1.68 x 10²²

(e) 2.45 x 10²²

7.

Which one of the samples contains the most
atoms?

(a) 1 mol of CO₂(g)

(b) 1 mol of UF₆(g)

(c) 1 mol of CH₃COCH₃(l)

(d) 1 mol of He(g)

(e) all contain the same number of atoms

8.

Which one of the samples contains the most
molecules?

(a) 1 mol of CO₂(g)

(b) 1 mol of UF₆(g)

(c) 1 mol of CH₃COCH₃(l)

(d) 1 mol of He(g)

(e) all contain the same number of molecules

9.

Which one of the samples has the largest mass?

(a) 1 mol of CO₂(g)

(b) 1 mol of UF₆(g)

(c) 1 mol of CH₃COCH₃(l)

(d) 1 mol of He(g)

(e) all have the same mass

10.

Which of the following statements is(are) FALSE?

1. The percent by mass of each element in a compound depends on the amount of the compound.

2. The mass of each element in a compound depends on the amount of the compound.

3. The percent by mass of each element in a compound depends on the amount of element present in the compound.

(a) 2 and 3

(b) 1 only

(c) 1 and 2

(d) 1, 2 and 3

(e) another combination

11.

Guanidin, HNC(NH₂)₂, is a fertilizer. To three significant figures, what is the percent by mass of nitrogen in the fertilizer?

(a) 45.2%

(b) 49.4%

(c) 54.8%

(d) 65.1%

(e) 71.1%

12.

Calculate the percent, by weight, of carbon in 154 g of C₄H₈O₃?

(a) 46%

(b) 31%

(c) 72%

(d) 27%

(e) 55%

13.

Analysis of a sample of a covalent compound showed that it contained 14.4% hydrogen and 85.6% carbon by mass. What is the empirical formula for the compound?

(a) CH

(b) CH₂

(c) CH₃

(d) C₂H₃

(e) none of these

14.

An oxide of lead contains 90.65% Pb, by weight. The empirical formula is:

(a) Pb

(b) PbO

(c) Pb₃O₄

(d) Pb₂O₃

(e) PbO₂

15.

A 0.500 g sample of a compound containing only antimony and oxygen was found to contain 0.418 g of antimony and 0.082 g of oxygen. What is the simplest formula for the compound?

(a) SbO

(b) SbO₂

(c) Sb₃O₄

(d) Sb₂O₅

(e) Sb₂O₃

16.

A compound contains, by mass, 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen. A 0.320 mole sample of this compound weighs 28.8 g. The molecular formula of this compound is:

(a) C₂H₄O₂

(b) C₃H₆O₃

(c) C₂H₄O

(d) CH₂O

(e) C₄H₇O₂

17.

What mass of cerussite, PbCO₃, would contain 35.0 grams of lead?

(a) 27.1 g

(b) 45.1 g

(c) 42.4 g

(d) 35.6 g

(e) 51.7 g

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Answers:

1.
(b)
2.
(d)
3.
(b)
4.
(d)
5.
(d)
6.
(a)
7.
(c)
8.
(e)
9.
(b)
10.
(b)
11.
(e)
12.
(a)
13.
(b)
14.
(c)
15.
(e)
16.
(b)
17.
(b)

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Chemical Formulas & Composition Stoichiometry
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Chemical Periodicity
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Chemical Bonding
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Molecular Structure/Covalent Bonding Theories|
Molecular Orbital Theory
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Acids/Bases/Salts – Calculations (including balancing redox rxns)
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Gases
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Solutions
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| Thermodynamics | Kinetics | Equilibrium | Aqueous Equilibrium – Acids/Bases/Salts | Aqueous Equilibrium – Buffers & Titrations |
| Aqueous Equilibrium – Slightly Soluble Salts | Electrochemistry | Metallurgy | Metal Properties & Rxns | Nonmetals & Metalloids |
| Coordination Compounds | Nuclear Chemistry | Organic Chem – Formulas/Names/Properties | Organic Chem – Shapes/Rxns/Biopolymers |

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