ACS Final Review

Structure

100

Which ion has twenty-six electrons?

a) Cr²⁺

b) Fe²⁺

c) Ni²⁺

d) Cu²⁺

Ni²⁺

200

The best Lewis structure of N₂H₂ shows...

a) a nitrogen-nitrogen triple bond

b) a nitrogen-nitrogen single bond

c) each nitrogen with one nonbonding electron pair

d) each nitrogen with two nonbonding electron pairs

Each nitrogen with one nonbonding electron pair

300

What is the valence electron configuration for the element in Period 5, Group 3A?

5s²5p¹

400

Which electronic transition in a hydrogen atom is associated with the largest emission of energy?

a) n=2 to n=1

b) n=2 to n=3

c) n=2 to n=4

d) n=3 to n=2

n=2 to n=1

500

If gallium, atomic number 31, combines with selenium, atomic number 34, what is the most likely formula based on your knowledge of the periodic nature of the elements?

a) GaSe

b) GaSe₂​

c) Ga₂Se

d) Ga₂Se₃

​​​

Ga₂Se₃

Calculations

100

How many moles of hydrogen atoms are in six moles of Ca(OH)₂?

2

200

What is the mass of 1.75 moles of Zn?

114 g

300

What is the empirical formula for a compound that is comprised of 54.0% sodium, 8.50% boron, and 37.5% oxygen by mass?

Na₃BO₃

400

A 3.41 x 10^-6 g sample is known to contain 4.67 x 10¹⁶ molecules. What is this compound?

a) CH₄

b) CO₂

c) H₂O

d) NH₃

CO₂

500

A molecular compound is found to consist of 30.4% nitrogen and 69.6% oxygen. If the molecule contains 2 atoms of nitrogen, what is the molar mass of the molecule? 

92 g/mol

Stoichiometry

100

What are the coefficients for each substance in the chemical reaction when balanced?

__C₇H₁₄O₂ + ___O₂ ---> ___CO₂ + ___H₂O

2, 19, 14, 14

200

How many moles of water are necessary to react completely with 8.0 mol PCl₅?

PCl₅ + 4H₂O ---> H₃PO₄ + 5HCl

32 mol

300

A mixture of 9 mol F₂ and 4 mol S are allowed to react. How many moles of F₂ remain after 3 mol of S have reacted?

3F₂ + S ---> SF₆

0

400

What amount of excess reagent remains when 4.0 g zinc react with 2.0 g phosphorus? 

3Zn + 2P ---> Zn₃P₂

0.70 g P

500

Epimolar amounts of nitrogen, hydrogen, and argon are placed in a reaction chamber. The amount of which substance/s will determine the amount of ammonia produced in the reaction below if the reaction goes to completion? 

N₂(g) + 3H₂(g) ---> 2NH₃(g)

Hydrogen

Heat and Enthalpy

100

If a system's internal energy increases by 250 kJ after the addition of 375 kJ of energy as heat, what was the value of the work in the process?

-125 kJ

200

When a 45.0 g sample of an alloy at 100.0^oC is dropped in 100.0 g of water (specific heat = 4.184 J/g K) at 25.0^oC, the final temperature is 37.0^oC. What is the specific heat of the alloy?

1.77 J/g ^oC

300

Calculate the enthalpy of combustion of ethylene, C₂H₄ (ΔH⁰_f= 52.3 kJ/mol), at 25.0^oC and one atmosphere of pressure. 

C₂H₄(g) + 3O₂(g) ---> 2CO₂(g) + 2H₂O(l)

ΔH⁰_f of CO₂(g) = -393.5 kJ/mol

ΔH⁰_f of H₂O(l) = -285.8 kJ/mol

-1411 kJ/mol

400

The standard enthalpy change for the formation of silver chloride from its elements (ΔH⁰_f = -127.1 kJ/mol) is ____ than the enthalpy change for the formation of silver bromide (ΔH⁰_f = -100.4 kJ/mol)

a) more exothermic

b) less exothermic

c) more endothermic

d) less endothermic

More exothermic

500

What is the standard enthalpy change for this reaction?

Mg(s) + 2HCl(aq) ---> MgCl₂(aq) + H₂(g)

ΔH⁰_f for HCl(aq) = -167.2 kJ/mol

ΔH⁰_f for MgCl₂(aq) = -641.6 kJ/mol

-307.2 kJ/mol

Reactions

100

Which is the strongest electrolyte in dilute aqueous solution?

a) HClO₄

b) HCN

c) HF

d) HNO₂

HClO₄

200

What is the molar concentration of the chloride ion in a 3.0 M CaCl₂ solution?

a) 6.0 M

b) 3.0 M

c) 1.5 M

d) 1.0 M

6.0 M

300

What volume (in mL) of a 0.0557 M Sr(OH)₂ solution is needed to neutralize 36.4 mL of a 0.0750 M HNO₃ solution? 

24.5 mL

400

What is the oxidation number of chlorine in NaClO₂?

+3

500

What is/are the spectator ion/s in this reaction?

HC₂H₃O₂(aq) + NaOH(aq) ---> NaC₂H₃O₂(aq) + H₂O(l)

a) C₂H₃O₂^-

b) H⁺ and OH^-

c) Na⁺

d) Na⁺ and C₂H₃O₂^-

Na⁺ only