Chemistry VI Exam Chapters 19-22,25

What is the coefficient of the dichromate ion (Cr2O72-) when the following equation is balanced? Fe2+ + Cr2O72- → Fe3+ + Cr3+ (acidic solution) a. 4 b. 3 c. 1 d. 2

c. 1

In a 0.1000 M solution of methanoic acid, [H+] = 3.5 x 10-3. Calculate the Ka of this acid. a. 5.0 x 10-4 b. 8.7 x 10-4 c. 1.3 x 10-4 d. 4.2 x 10-4

c. 1.3 x 10-4

In a 0.2000 M solution of a monoprotic weak acid, [H+] = 9.86 x 10-4 M. What is the Ka of this weak acid? a. 8.13 x 10-6 b. 1.10 x 10-6 c. 4.89 x 10-6 d. 3.44 x 10-6

c. 4.89 x 10-6

How many milliliters of 0.45 M HCl will neutralize 25.0 mL of 1.00 M KOH? a. 45 mL b. 90 mL c. 56 mL d. 23 mL

c. 56 mL

How many moles of potassium hydroxide are needed to neutralize 2.56 mol of phosphoric acid? 3 KOH (aq) + H3PO4 (aq) --> K3PO4 (aq) + 3 H20 a. 5.92 mol b. 8.13 mol c. 7.68 mol d. 2.00 mol

c. 7.68 mol

What is the change in atomic number after the beta decay? a. It decreases by 2. b. It increases by 2. c. It increases by 1. d. It decreases by 1.

c. It increases by 1.

Which element is reduced in the following chemical reaction? P4(s) + O2(g) --> P4O10(s) a. potassium b. phosphorus c. oxygen d. platinum

c. oxygen

Which is the correct name for the alkene shown below? a. 2-methyl-3-methyl-2-pentene b. 2,3-dimethyl-3-pentene c. 3-ethyl-2-methyl-2-butene d. 2,3-dimethyl-2-pentene

d. 2,3-dimethyl-2-pentene

What is the change in atomic number after the alpha decay? a. It increases by 4. b. It decreases by 4. c. It increases by 2. d. It decreases by 2.

d. It decreases by 2.

What are the products of a reaction between an acid and a base? a. a weak acid and a weak base b. two aqueous salts c. sugar and benzene d. a salt and water

d. a salt and water

Which substance is the oxidizing agent in the reaction below? Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O a. lead(II) sulfate b. water c. lead d. sulfuric acid e. lead(II) oxide

e. lead(II) oxide

Match each description with hte correct term by writing its letter in the blank. 1. Any electrochemical cell used to convert chemical energy into electrical energy 2. One part of a voltaic cell in which either reduction or oxidation occurs 3. The electrode at which oxidation occurs 4. A tube containing a strong electrolyte, which allows transport of ions between the half-cells 5. The electrode at which reduction occurs

e. voltaic cell c. half-cell b. anode d. salt bridge a. cathode

For each sentence, match the type of cell. _ Electrons are pushed by an outside power source. _ Reduction occurs at the cathode and oxidation occurs at the anode. _ The flow of electrons is the result of a spontaneous redox reaction. _ Electrons flow from the anode to the cathode. For each sentence, match the type of cell.

electrolytic cells Electrons are pushed by an outside power source. both voltaic and electrolytic cells Reduction occurs at the cathode and oxidation occurs at the anode. voltaic cells The flow of electrons is the result of a spontaneous redox reaction. both voltaic and electrolytic cells Electrons flow from the anode to the cathode.

What is the name of the process that is the opposite of oxidation? ______________

reduction

What is the oxidation number of potassium in KMnO4? a. 0 b. +1 c. -1 d. +3 e. +2

b. +1

What is the correct coefficient for the electrons in the following half-reaction: Ni6+ + ___e- → Ni a. 4 b. 6 c. 2 d. 3 e. 5

b. 6

Match the name of the straight-chain alkane with the number of carbon atoms it contains. 1. nonane 2. propane 3. heptane 4. butane

b. 9 c. 3 a. 7 d. 4

Which are correct structural formulas for pentane? a. C5H12 b. CH3(CH2)3CH3 c. CH3CH2CH2CH2CH3 d. C—C—C—C—C

b. CH3(CH2)3CH3 c. CH3CH2CH2CH2CH3 d. C—C—C—C—C

Which statements are true about carbon's ability to form bonds? (There are two.) a. Carbon atoms always form three covalent bonds. b. Carbon atoms can form stable bonds with other carbon atoms. c. Carbon atoms have four valence electrons.

b. Carbon atoms can form stable bonds with other carbon atoms. c. Carbon atoms have four valence electrons.

Which are true about oxidation? (There are three.) a. All oxidation processes involve burning. b. Rusting is an example of oxidation. c. Bleaching is an example of oxidation. d. Gasoline, wood, coal, and natural gas (methane) can all burn in air, producing oxides of carbon.

b. Rusting is an example of oxidation. c. Bleaching is an example of oxidation. d. Gasoline, wood, coal, and natural gas (methane) can all burn in air, producing oxides of carbon.

The gain of electrons by an element is called ________. a. sublimation b. reduction c. fractionation d. oxidation e. disproportionation

b. reduction

Which of these salts would hydrolyze to produce an acidic aqueous solution, and why? a. KC2H3O2 b. LiCl c. NaHCO3 d. (NH4)2SO4

A. Basic B. Neutral C. Basic D. Acidic

Write the oxidation number, or the sum of the oxidation numbers, for the given atoms, ions, or compounds. _ Cu(II) ion _ Hydrogen in water _ Chlorine in sodium chloride (NaCl) _ Potassium sulfate (K2SO4)

+2 Cu(II) ion +1 Hydrogen in water -1 Chlorine in sodium chloride (NaCl) 0 Potassium sulfate (K2SO4)

What is a battery?

A Battery is a group of voltaic cells connected together. An alkaline battery is a dry cell, whereas a lead storage battery is considered to be a true battery.

Explain why a buffered solution cannot absorb an unlimited amount of acid or base.

A buffered solution cannot absorb an unlimited amount of acid or base because it has a buffer capacity. The buffer capacity limits the amount of acid and or base that you can add to a buffered solution before a significant change in the pH of the solution occurs.

Fill in the name of the hydrocarbon. For all alkenes and alkynes, the double or triple bond is on the first carbon. Number of Carbons Alkane Alkene Alkyne C6 _ _ _ C7 _ _ _ C8 _ _ _

C6 hexane . 1-hexene Correct. 1-hexyne Correct. C7 heptane Correct. 1-heptene Correct. 1-heptyne Correct. C8 octane Correct. 1-octene Correct. 1-octyne Correct.

For each binary ionic compound listed in the table, write the symbols for both ions, their ionic charges, and their oxidation numbers. Compound Ions Ionic Charges Oxidation Numbers NaCl _ _ _ _ _ _ CaF2 _ _ _ _ _ _

Compound Ions Ionic Charges Oxidation Numbers NaCl Na^+ Correct. Cl^- Correct. 1+ Correct. 1- Correct. +1 Correct. -1 Correct. CaF2 Ca^2+ Correct. F^- Correct. 2+ Correct. 1- Correct. +2 Correct. -1 Correct.

Is this a redox reaction? MgCl2 + 2KBr --> MgBr2 + 2KCl Yes No

No

For each process described below, label it O if it is an oxidation or R if it is a reduction. _ Addition of oxygen to carbon or carbon compounds _ Removal of a metal from its ore _ Complete gain of electrons in an ionic reaction _ Shift of electrons away from an atom in a covalent bond _ Gain of hydrogen by a covalent compound For each process described below, label it O if it is an oxidation or R if it is a reduction.

O Addition of oxygen to carbon or carbon compounds R Removal of a metal from its ore R Complete gain of electrons in an ionic reaction O Shift of electrons away from an atom in a covalent bond R Gain of hydrogen by a covalent compound

Explain why solutions of salts that hydrolyze water do not have a pH of 7.

Solutions of salts that hydrolyze water do not have a ph of 7 as the salts primarily consist of an acid and a cation wich form a base. The Salts that produce the acidic solutions have positive ions that release hydrogen ions into the water. Salts that produce basic solutions, on the other hand, have negative ions that attract hydrogen ions from water. So the scale of solutions of salt hydrolyzing is changing and is usually at a pH from around 6 to 7. But the solutions of salt hydrolyzing the water never settle at a neutral pH of 7 as it is constantly reacting and changing.

Name two advantages of fuel cells.

Two advantages of fuel cells are that they have overcome disadvantages associated with lead storage batteries as the are able to renew their electrodes. Therefore they do not have to be recharged which is a huge advantage and also they can be designed to emit no air pollutants. Thus they operate quietly and they are more cost-effective due to their conventional electrical generator.

What is the change in mass number after the alpha decay? a. It decreases by 4. b. It decreases by 2. c. It increases by 4. d. It increases by 2.

a. It decreases by 4.

What types of substance can be combined to make a buffer solution? a. a weak acid and one of its salts or a weak base and one of its salts b. a strong base and a strong acid or a weak base and a weak acid

a. a weak acid and one of its salts or a weak base and one of its salts

Which are true about electrochemical cells? (There are three.) a. For an electrochemical cell to be a source of useful electric energy, the electrons must pass through an external circuit. b. An electrochemical cell either produces an electric current or uses an electric current to produce a chemical change. c. An electrochemical cell can convert chemical energy to electrical energy, but not electrical energy into chemical energy. d. Redox reactions occur in electrochemical cells.

a. b. d.