Final Review

Thermochemistry

100

Ethanol is a common fuel that releases energy when combusted. The balanced equation for the combustion of ethanol is:

C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O       ΔH=−1367 kJ

How many grams of ethanol must be burned to produce 750. kJ heat?

25.3 g

200

Calculate the standard enthalpy change for 

Fe₂O_3 (s) + 3H_{2 (g)} ⟶ 2Fe(s) + 3H₂O_(l)

Fe₂O_3 (s) ΔHf° (kJ/mol): -824.2

H₂O_(g) ΔHf° (kJ/mol): -241.8

H₂O_(l) ΔHf° (kJ/mol): -285.8 

-33.2 kJ

300

Using the following bond enthalpies:

H-H (432 kJ/mol)

O=O (496 kJ/mol)

H-O (463 kJ/mol)

Determine the enthalpy of reaction for:

H_{2 (g)} + 1/2 O_{2 (g)} ---> H₂O_(g)

-246 kJ

400

Given:

C_(s) + O_{2 (g)} → CO_{2 (g)}    ΔH = -393.5 kJ

H_2 (g) + 1/2 O_2 (g) → H₂O_(l)    ΔH = -285.8 kJ

2C₂H_6 (g) + 7O_{2 (g)} → 4CO_2 (g) + 6H₂O_(l)  ΔH = -3119.6 kJ

Calculate the enthalpy change for the following reaction:

2C_(s) + 3H_2 (g) → C₂H_6 (g)

-84.6 kJ

500

Use the following data to calculate the enthalpy of formation of strontium chloride (SrCl₂₎:

Enthalpy of sublimation of Sr = + 164 kJ/mol
First IE for Sr = + 549 kJ/mol

Second IE for Sr = + 1064 kJ/mol  

Enthalpy of dissociation of Cl₂ = + 243 kJ/mol 

Electron Affinity of Cl = - 349 kJ/mol
Lattice energy of SrCl₂ = - 2150 kj/mol

-828 kJ/mol

Precipitation Reactions

100

What are the spectator ions of the following reaction

NaCl (aq) + AgNO₃ (aq) → AgCl (s) + NaNO₃ (aq)

Na⁺ and NO₃^-

200

Identify the precipitate, if there is one:

BaCl₂ + K₂SO₄ → 2KCl + BaSO₄

BaSO₄ (s)

300

Write the balanced Complete Ionic Equation of the following reaction:

Pb(NO₃)_{2 (aq)} + KI_(aq) → PbI_2 (s) + KNO_3 (aq)

Pb²⁺_(aq) + 2NO₃^-_(aq) + 2K⁺_(aq) + 2I^-_(aq) → PbI_2 (s) + 2K⁺_(aq)  + 2NO₃^-_(aq)

400

Write the balanced Net Ionic equation

CaCl_{2 (aq)} + Na₂CO_{3 (aq)} → CaCO_{3 (s)} + NaCl_(aq)

Ca²⁺_(aq) + CO₃^2-_(aq) → CaCO_3 (s)

500

Write the balanced chemical equation including states when you mix aqueous silver nitrate and aqueous ammonium chromate.

2AgNO_{3 (aq)} + (NH₄)₂CrO_{4 (aq)} → Ag₂CrO_{4 (s)} + 2NH₄NO_{3 (aq)}

Acids and Bases

100

What is the Bronsted-Lowry definition of an acid and base?

Acid: proton (H⁺) donor

Base: proton (H⁺) acceptor

200

Which of the following is a strong acid?

- HCl

- CH₃COOH

- HF

- H₂CO₃

HCl

300

Which of the following is a weak base?

- NaOH

- Fe(OH)₂

- KOH

- Ba(OH)₂

Fe(OH)₂

400

Write the balanced net ionic equation.

H₂SO_{4 (aq)} + NaOH_(aq) → Na₂SO_4(aq) + H₂O_(l)

H⁺_(aq) + OH^-_(aq) → H₂O_(l)

500

Write the balanced net ionic equation.

HF_(aq) + NaOH_(aq) → NaF_(aq) + H₂O_(l)

HF_(aq) + OH^-_(aq) → F^-_(aq) + H₂O_(l)

Redox Reactions

100

What is the oxidation number of Pb_(s)?

0

200

Assign oxidation numbers to each element in the following compound:

H₂SO₄

H: +1

S: +6

O: -2

300

Balance the given net ionic redox equation

Zn_(s) + Cu⁺_(aq) → Zn²⁺_(aq) + Cu_(s)

Zn_(s) + 2Cu⁺_(aq) → Zn²⁺_(aq) + 2Cu_(s)

400

Identify the elements being oxidized and reduced.

Zn_(s) + CuSO_{4 (aq)} → ZnSO_{4 (aq)} + Cu_(s)

Oxidized: Zinc

Reduced: Copper

500

Identify the oxidizing and reducing agent.

2KrF₂ + 2H₂O → 2Kr + 4HF + O₂

Oxidizing agent: Krypton in KrF₂

Reducing agent: Oxygen in H₂O

Limiting Reagents

100

Balance the reaction and determine how many grams of HCl are required to react completely with 45.0g of Mg.

Mg + HCl ⟶ MgCl₂ + H₂

135g of HCl

200

How many mL of 0.25 M NaOH solution are necessary to neutralize 80 mL of 0.3 M HCl?

96mL

300

Determine the limiting reagent when 3.22g of Al reacts with 4.96g of HBr.

Unbalanced Equation:

Al + HBr → AlBr₃ + H₂

Limiting Reagent: HBr

400

Phosphorous reacts with bromine to form phosphorous tribromide. If 35.0 grams of bromine react completely to form 27.9 grams of phosphorous tribromide, what is the percent yield?

70.63%

500

26.62g of FeS₂ reacts with 5.44g of O_2. For the reactant in excess, how many grams are left over at the end of the reaction?

Unbalanced Equation

FeS₂ + O₂ → Fe₂O₃ + SO₂

19.2g FeS₂