Chemistry B: Lesson 8 Quiz Review

In the reaction Fe2O3 + 3CO → 2Fe + 3CO2, which element gains electrons and how many does each atom gain? 1.) Iron gains 3 electrons. 2.) Oxygen gains 2 electrons. 3.) Iron gains 2 electrons. 4.) Carbon gains 4 electrons.

1 (The oxidation state of iron in Fe2O3 is +3 but in Fe it is 0. This means the iron atoms have gained 3 electrons in the reaction.)

When a Cu(^+2) ion gains electrons it forms a Cu atom. This process is known as what? 1.) oxidation 2.) catalyzation 3.) reduction 4.) titration

3 (The gain of electrons is reduction.)

How can the corrosion of a metal be prevented? 1.) Use a "sacrificial" metal 2.) Remove paint from a metal 3.) React the metal with an acid 4.) Add water

1

How does the presence of a salt effect the processes of corrosion? 1.) Salt speeds corrosion because it allows electrons to transfer more easily. 2.) Salt slows corrosion because it inhibits the movement of oxygen. 3.) Salt speeds corrosion because it adds extra electrons to the reaction. 4.) Salt slows corrosion because it dissolves in water.

1

In the reaction 2KNO3 → 2KNO2 + O2, what element was oxidized and what element was reduced? 1.) Potassium is oxidized and nitrogen is reduced. 2.) Oxygen is oxidized and nitrogen is reduced. 3.) Potassium is oxidized and oxygen is reduced. 4.) Nitrogen is oxidized and potassium is reduced.

2

What happens when an element undergoes oxidation? 1.) The element gains electrons. 2.) The element loses electrons. 3.) The element changes from a metal to a nonmetal. 4.) The element achieves the electron configuration of a halogen.

2

Which equation below shows an oxidation-reduction reaction? 1.) MgCl2 + H2SO4 → MgSO4 + 2HCl 2.) Cr + 2HCl → CrCl2 + H2 3.) LiNO3 + KOH → LiOH + KNO3 4.) HCl + NaOH → NaCl + H2O

2

Which of the following describes reduction? 1.) increase in oxidation number 2.) gain of hydrogen 3.) lose of electrons 4.) gain of oxygen

2

Which of the following is a clue that a redox reaction occurred? 1.) no oxygen is used 2.) color change 3.) a base neutralized an acid 4.) the oxidation number remains constant

2

Which of the following ions is most likely to be an oxidizing agent? 1.) ClO2- 2.) ClO4- 3.) Cl- 4.) ClO3-

2 (ClO4- is the most likely to be an oxidizing agent because the Chlorine ion is at its highest oxidation state.)

A number which is assigned to each atom or ion in a compound which explains its degree of oxidation or reduction is called 1.) Reducing agent 2.) Reduction number 3.) Oxidation number 4.) Oxidizing agent

3

All of the following are typically redox reactions except 1.) decomposition reactions 2.) combination reactions 3.) double displacement reactions 4.) single displacement reactions

3

What is the oxidation number for each of the elements in SO3? 1.) S is +3 and O is -1 2.) S is +5 and O is -2. 3.) S is +6 and O is -2. 4.) S is +1 and O is -3

3

Which compound represents a hydrogen with an oxidation number of -1? 1.) (NH4)2S 2.) H2SO4 3.) NaH 4.) H2O

3

The reactant in a redox reaction that readily accepts electrons is called a/an: 1.) corrosive 2.) reducing agent 3.) oxidation number 4.) oxidizing agent

4

What is the reducing agent and the oxidizing agent in the redox equation SbCl5 + KI → SbCl3 + KCl + I2? 1.) KI is the oxidizing agent and SbCl5 is the reducing agent. 2.) I2 is the oxidizing agent and KCl is the reducing agent. 3.) KI is the oxidizing agent and I2 is the reducing agent. 4.) SbCl5 is the oxidizing agent and KI is the reducing agent.

4

Which of the following are used to balance the atoms of redox reaction in an acidic solution? 1.) H2O and OH- 2.) H+ and OH- 3.) H+ and Cl- 4.) H2O and H+

4

Which is the correct balanced equation for the redox reaction HNO3 + Fe → Fe(NO3)3 + NO + H2O ? a.) 4 HNO3 + Fe → Fe(NO3)3 + NO + 2 H2O b.) HNO3 + 2Fe → Fe(NO3)3 + NO + 2 H2O c.) HNO3 + Fe → Fe(NO3)3 + NO + H2O d.) 4 HNO3 + 2 Fe → 2 Fe(NO3)2 + NO + 2 H2O

a

Put the following steps in order for using the half-reaction method to balance a redox reaction. 1 Balance the atoms in the half-reaction 2 Multiply each half-reaction to equalize the number of electrons 3 Write separate half-reactions for oxidation and reduction 4 Add the balanced half-reactions to represent the overall equation a.) 3, 1, 2, 4 b.) 3, 2, 4, 1 c.) 2, 3, 1, 4 d.) 1, 2, 3, 4

a (write, balance, multiply, add [WMBA])

What is the oxidation state for sulfur in a sulfate ion (SO4^-2)? a.) +4 b.) +2 c.) +6 d.) +8

c