Holt Ch 19 PPt

Multiple Choice

Which of the following correctly represents the balanced half-reaction for the reduction of permanganate ion in acidic solution?

• MnO4- + 8H+ + 5e- → Mn2+ + 4H2O

• MnO4- + 2e- → Mn2+ + 2H2O

• MnO4- + 8H+ → Mn2+ + 4H2O

• MnO4- + 5e- → Mn2+ + 2H2O

Multiple Choice

Which of the following best describes a redox reaction?

• A reaction involving the transfer of electrons between species

• A reaction that only involves the combination of two elements

• A reaction where only oxidation occurs

• A reaction where only reduction occurs

Open Ended

What are the main differences between the steps for writing the half-reaction for oxidation and for reduction in the half-reaction method?

Open Ended

Why is it important to understand oxidation and reduction processes in chemistry?

Open Ended

What is a redox reaction and how is it related to oxidation and reduction?

Fill in the Blank

A species whose oxidation number increases is said to be ___.

Multiple Choice

Which of the following statements best describes an oxidation process?

• A reaction in which the oxidation state of an element increases.

• A reaction in which the oxidation state of an element decreases.

• A reaction in which the oxidation state of an element remains unchanged.

• A reaction in which electrons are gained by an element.

Multiple Choice

Which rule is used to determine the oxidation number of oxygen in most compounds?

• Oxygen has an oxidation number of -2 unless it is combined with fluorine or in a peroxide.

• The oxidation number of any uncombined element is 0.

• The oxidation number of a monatomic ion equals the charge on the ion.

• The more-electronegative element in a binary compound is assigned the number equal to the charge it would have if it were an ion.

Open Ended

Explain how to assign oxidation numbers to the elements in HNO3 using the rules provided.

Multiple Choice

Which of the following is true about reduction processes?

• They involve a decrease in the oxidation state of an element.

• They involve an increase in the oxidation state of an element.

• They involve no change in the oxidation state of an element.

• They always involve the loss of electrons.

Multiple Choice

Which of the following represents the oxidation half-reaction in the reaction between nitric acid and copper?

• Cu → Cu2+ + 2e−

• 2NO3− + 2e− + 4H+ → 2NO2 + 2H2O

• Cu + 2NO3− + 4H+ → Cu2+ + 2NO2 + 2H2O

• 2NO2 + 2H2O → 2NO3− + 2e− + 4H+

Multiple Select

Which statements about the reaction between hydrogen and chlorine are correct?

• A covalent bond forms from the sharing of two electrons.

• The pair of electrons is more strongly attracted to the hydrogen atom.

• Chlorine has a higher electronegativity than hydrogen.

• Neither atom has totally lost or totally gained any electrons.

Open Ended

Explain how the sharing of electrons in a covalent bond during a redox reaction differs from the complete transfer of electrons in an ionic bond.

Multiple Choice

Which of the following is the first step in the half-reaction method for balancing redox equations?

• Assign oxidation numbers.

• Write the formula equation and then the ionic equation.

• Balance the atoms.

• Combine the half-reactions.

Open Ended

In the particle model for a redox reaction, what happens to the zinc atoms and copper ions before and after the reaction?

Multiple Choice

Which of the following steps is necessary to conserve charge in the half-reaction method?

• Combine the half-reactions and cancel out anything common to both sides.

• Assign oxidation numbers to all elements.

• Adjust the coefficients in front of the electrons so the number lost in oxidation equals the number gained in reduction.

• Write the formula equation.

Open Ended

Describe the steps involved in balancing a redox equation using the half-reaction method.

Fill in the Blank

Balance the overall charge in a half-reaction by adding ___ as needed.

Fill in the Blank

In a redox equation, the total number of electrons lost must be ___ to the total number of electrons gained.

Multiple Choice

According to the steps for balancing redox equations using the half-reaction method, which of the following should be balanced first in each half-reaction?

• Oxygen atoms

• Hydrogen atoms

• Atoms other than hydrogen and oxygen

• The overall charge

Open Ended

Describe the process you would use to verify that a redox equation is properly balanced using the half-reaction method.

Multiple Choice

Which of the following best describes the process of assigning oxidation numbers?

• Determining the number of protons in an atom

• Identifying the charge an atom would have if electrons were transferred completely

• Counting the total number of atoms in a molecule

• Measuring the mass of a compound

Multiple Choice

What is the first step in the half-reaction method for balancing redox equations, as shown in the sample problem?

• Write the formula equation and then the ionic equation

• Assign oxidation numbers to each element and ion

• Write the half-reaction for oxidation

• Combine the half-reactions and cancel

Open Ended

What is an oxidation-reduction (redox) reaction?

Multiple Choice

Which ions or molecules are retained when assigning oxidation numbers in the half-reaction method?

• Only those whose oxidation numbers change

• All ions and molecules

• Only neutral molecules

• Only cations

Open Ended

Explain how you would balance the charge in the oxidation half-reaction for iron, based on the steps shown in the slides.

Fill in the Blank

Fill in the blank: To conserve charge, the coefficients of the half-reactions are adjusted so that the number of electrons lost in oxidation equals the number of electrons ___ in reduction.

Open Ended

After combining the half-reactions in the final step, what is the overall balanced redox equation for the reaction between MnO4- and Fe2+ in acidic solution?