ACS Final Review 1 - CHEM 109

Nomenclature

100

What is the name of the following compound?

P₂Cl₅

Phosphorus pentachloride

200

What is the formula for the following compound?

Aluminum iodide

AlI₃

300

What is the name of the following compound?

CoBr₂

Cobalt (II) bromide

400

What is the formula for the following compound?

Calcium phosphate

Ca₃(PO₄)₂

500

What is the formula for the following acid?

Chloric acid

HClO₃

Isotopes

100

What is the definition of an isotope?

Atoms with the same number of protons but different number of neutrons.

200

An ionic isotope of oxygen is denoted as follows: ¹⁸O^-2

How many neutrons are in this isotope?

8 neutrons

300

How does the molar mass of an element as listed on the periodic table relate to isotopes of that element?

The molar mass of an element on the periodic table is the average atomic mass of all naturally existing isotopes of that element.

400

What is the formula you might use for calculating average atomic mass, or percent abundances of isotopes? You may use a general formula or apply it to a specific element.

Specific for carbon isotopes:

(mass ¹²C)*(fraction ¹²C) + (mass ¹³C)*(fraction ¹³C) = average atomic mass

500

Assume the atomic mass of ¹²C is 12amu and ¹³C is 13amu, and that these are the only isotopes of carbon that exist naturally. The average atomic mass of carbon is 12.01amu. What are the percent abundances of these two isotopes?

¹²C is 98.89%

¹³C is 1.110%

Avogadro's Number and Stoichiometry

100

How many atoms of sulfur are in 1.5mol S₈ (yellow sulfur)?

7.2*10²⁴ S atoms

200

In grams, what is the mass of 2.0*10²² molecules of Fe(OH)₃?

Bonus 100pts: What is the name of Fe(OH)₃?

3.6g Fe(OH)₃

Bonus: iron (III) hydroxide

300

In the reaction below, how many moles of Cl₂ are required to make 3 moles of PCl₃?

P₄ + 4Cl₂ -> 6PCl₃

2 moles of Cl₂

400

In the reaction below, how many moles of P₄ are required to react completely with 5 moles of Cl₂?

P₄ + 4Cl₂ -> 6PCl₃

1.25 moles P₄

500

What quantity of HCl, in grams, can a tablet of 0.750g Al(OH)₃ neutralize? Use the reaction below as a guide:

Al(OH)₃ + 3HCl -> AlCl₃ + 3H₂O

Bonus 100pts: What is the name of the acid in this reaction?

1.05g HCl

Bonus: hydrochloric acid

% Composition and Empirical Formula

100

What is the percent composition by mass of carbon in sodium carbonate?

11.33% C

200

What is the percent composition by mass of N in NH₄NO₃?

Bonus 200pts: What is the name of the compound?

35% N

Bonus: ammonium nitrate

300

The empirical formula for a compound is found to be P₂O₅. The molar mass of the actual compound is 283.88g/mol. What is the molecular formula for the compound?

P₄O₁₀

400

A compound is 43.6% P and 56.4% O by mass. What is its empirical formula?

P₂O₅

500

Isopropyl alcohol (rubbing alcohol) is 60.0% C, 13.4% H, and 26.6% O by mass. What is its empirical formula?

C₃H₈O

Limiting Reactant and Percent Yield

100

What is the formula for percent yield?

(actual yield / theoretical yield) * 100 = percent yield

200

If the actual yield of a reaction is 13.44g, and the theoretical yield is 15.60g, what is the percent yield for the reaction?

86.15%

300

A reaction with a theoretical yield of 30.1g was allowed to progress. The percent yield of the reaction was 90.7%. What was the actual yield, in grams?

27.3g

400

What is the theoretical yield of a reaction between 3.65g H₂ gas and 26.7g O₂ gas? Provide answer in moles. Reaction is given below:

2H₂ + O₂ -> 2H₂O

1.67 moles H₂O

500

How much excess reactant is left over when 20.4g Fe and 5.73g O₂ react?

4Fe + 3O₂ -> 2Fe₂O₃

Bonus 100pts: What is the name of the product of this reaction?

7.1g Fe excess

Bonus: iron (III) oxide