CHEM-1A Unit 1 Review

Conversions

100

1,000,000 mL to L

1,000 L

200

2.578 pm to km

2.578 x 10^-15

300

5.500 L to g, D=3.450 g/mL

18,970 g

400

32,470 cm to miles

2.4211 miles

500

7.800 ft³ to yds³

0.2889 yds³

Isotopes

100

Name the parts of a Fe³⁺ atom

p⁺= 26

n⁰= 30

e^-= 23

200

Name the parts of a Boron-10 isotope.

p⁺= 5

n⁰= 5

e^-= 5

300

Argon has three naturally occurring isotopes: argon-36, argon-38, and argon-40. Based on argon’s reported atomic mass, which isotope exist as the most abundant in nature? Explain.

Argon-40 because the mass of Argon on the periodic table is about 40 amu.

400

Copper exists as a mixture of two isotopes. Copper-63 is 69.17% abundant and it has a mass of 62.9296 amu. Copper-65 is 30.83% abundant and it has a mass of 64.9278 amu. Calculate the atomic mass of copper.

63.55 amu

500

Bromine has two naturally occurring isotopes. Bromine-79 has a mass of 78.918 amu and is 50.69% abundant. Using the atomic mass reported on the periodic table, determine the mass of bromine-81, the other isotope of bromine.

80.92 amu

Nomenclature

100

S₁₀Br₃

Decasulfur Tribromide

200

CaCl₂

Calcium Chloride

300

Fe₂O₃

Iron (III) Oxide

400

HClO₃

Chloric Acid

500

H₂SO₂

Hyposulfurous Acid

Percent Composition

100

What is the total mass of H in H₂O?

11.19%

200

What is the total mass of C in C₁₂H₁₀O₆?

57.61%

300

What is the percent composition of Cl₂O₇?

Cl= 38.77%

O= 61.23%

400

What is the percent composition of CH₃COOH (acetic acid)?

C= 40.00%

H= 6.714%

O= 53.28%

500

Find the percent composition of Ca₃(PO₄)₂

Ca= 38.76%

P= 19.97%

O= 41.26%

Empirical/Molecular Formula

100

26.4% C, 3.3% H, and 70.3% O

Find the empirical formula

C₂H₃O₄

200

81.8 g C, 18.2 g H

Find the empirical formula

C₃H₈

300

20.2% Na, 37.6% S, and 42.2% O

MM= 682.8 g/mol

Empirical= Na₃S₄O₉

Molecular= Na₆S₈O₁₈

400

Determine the empirical and molecular formula of a compound composed of 18.24 g C, 0.51 g H, and 16.91 g F. The compound has a molar mass of 562.0 g/mol. Find the empirical and molecular formula.

Empirical= C₁₂H₄F₇

Molecular= C₂₄H₈F₁₄

500

The percent composition of an unknown substance is 75.42% C, 6.63% H, 8.38 N, and 9.57% O. The molar mass of the substance is 334.0 g/mol. Find the empirical and molecular formula.

Empirical= C₂₁H₂₂N₂O₂

Molecular= C₂₁H₂₂N₂O₂