Chemistry Unit 10 Flashcards by Ruby Janssen

What is the oxidation state on hydrogen?

Usually +1 but with metals -1

How well did you know this?

Not at all

Perfectly

What are the three possible oxidation states for oxygen?

Typically -2; with fluorine +2; when peroxide (O2) -1

How well did you know this?

Not at all

Perfectly

In oxidation is there an increase or decrease in the oxidation state?

Increase

How well did you know this?

Not at all

Perfectly

In oxidation is oxygen being added or removed?

Added

How well did you know this?

Not at all

Perfectly

In oxidation is hydrogen being added or removed?

Removed

How well did you know this?

Not at all

Perfectly

In reduction is the oxidation state increasing or decreasing?

Decreasing

How well did you know this?

Not at all

Perfectly

In reduction is oxygen being added or removed?

Removed

How well did you know this?

Not at all

Perfectly

In reduction is hydrogen being added or removed?

Added

How well did you know this?

Not at all

Perfectly

True or False: In an ox/red half reaction, you are only accounting for one atom/ion, unless the ion forms a diatomic

True

How well did you know this?

Not at all

Perfectly

In a ox/red half reaction, when do you put a coefficient in front of the ion?

When the atom is diatomic

How well did you know this?

Not at all

Perfectly

How do you find the oxidation state when there are more than one atoms of an element in a molecule with different oxidation states?

You find the average of them

How well did you know this?

Not at all

Perfectly

What are the steps to balancing an acidic reaction?

Half reactions
To Reduction Half:
Balance oxygen by adding H2O
Balance hydrogen by adding H+
Balance charge by adding e-

How well did you know this?

Not at all

Perfectly

What are the steps to balancing a basic reaction?

Half reactions based upon who is losing/gaining oxygen
Both Half Reactions:
Add H2O to balance oxygen
Add H+ to balance hydrogen
Add OH- to both sides (must have the same coefficient as the H+)
Add electrons to balance charge
Multiply and then simplify (the H+ and OH- should combine to make that many H2O on one side of each half reaction)

How well did you know this?

Not at all

Perfectly

What do you do differently to balance the basic redox reaction if there is no oxygen in one of the half reactions?

You skip the H2O and just add the H+ and OH-

How well did you know this?

Not at all

Perfectly

What type of cell is a spontaneous redox reaction happening in?

Voltaic cell

How well did you know this?

Not at all

Perfectly

What kind of current does a voltaic cell produce?

Electrical

How well did you know this?

Not at all

Perfectly

What is the purpose of a salt bridge in a voltaic cell?

To carry the ions - NOT ELECTRONS

How well did you know this?

Not at all

Perfectly

Is the anode or cathode negative in a voltaic cell?

Anode

How well did you know this?

Not at all

Perfectly

Is the anode or cathode positive in a voltaic cell?

Cathode

How well did you know this?

Not at all

Perfectly

In a voltaic cell, is the anode or cathode the more reactive metal?

The anode is the more reactive metal

How well did you know this?

Not at all

Perfectly

Which way do the electrons flow?

From anode to cathode

How well did you know this?

Not at all

Perfectly

Which element are all voltaic cells based off and what is the value assigned to that element?

Hydrogen - Standard Hydrogen Electrode; 0

How well did you know this?

Not at all

Perfectly

List the standard conditions for cells

1 mole/dm3 for all solutions, 298 K, 100 Kpa (for gasses)

How well did you know this?

Not at all

Perfectly

What is an inert Electrode and what are the typical ones used?

An inert Electrode is an Electrode that will not produce ions in the solution and is used if the cell does not include a metal. The typical ones are Pt and graphite

How well did you know this?

Not at all

Perfectly

In the standard reduction potentials chart in reference table, which value would you flip the sign of in order to calculate the voltage of an electrolytic cell?

The value that aligns with the oxidation half reaction

If you multiply a half reaction in a voltaic cell, what do you do to the voltage value of that half reaction?

Nothing! Never multiply voltage.

What value of delta G and E will create a spontaneous reaction?

Negative delta G and positive E

What value of delta G and E will create a nonspontaneous reaction?

Positive delta G and negative E

What type of cell performs a nonspontaneous redox reaction?

Electrolytic cells

What type of cell uses an external power source to start the chemical reaction?

Electrolytic cells

Is the anode or cathode negative in an electrolytic cell?

Cathode

Is the anode or cathode positive in an electrolytic cell?

Anode

Which type of cell has a salt bridge?

Voltaic cell

In a diagram of an electrolytic cell, there are two lines that represent the battery. How do you tell which line is the positive line?

The longer line

Define discharge

Got rid of the charge

What is the one big thing you must pay attention to when making redox reactions for electrolysis of molten salt versus of aqueous solutions?

In electrolysis of molten salt there is only one possibility for each half reaction, for aqueous solutions the water can be oxidized and reduced.

Write the equation for the reduction of water

2H2O(l) + 2e- -> H2(g) + 2OH-(aq)

Write the equation for the oxidation of water

2H2O(l) -> 4H+(aq) + O2(g) + 4e-

Will the reduction of H2O result in an increase or decrease in pH? Why?

Increase because OH- is being produced

Will the oxidation of H2O result in an increase or decrease in pH? Why?

Decrease because H+ is being produced

Is pure water a conductor of electricity?

What is the voltage for the reduction of water?

-.83 V

What is the voltage for the oxidation of water?

-1.23 V

How do you pick between the half reaction of H2O versus the half reaction of the solution in electrolysis of an aqueous solution?

Whichever reaction produces the more positive voltage is more spontaneous and therefore more likely to happen

In the electrolysis of NaOH(aq) the overall reaction is: 2H2O(l) -> 2H2(g) + O2(g) Which product is the anode and which is the cathode and why?

O2 is the anode and H2 is the cathode because two times as much H2 is produced, and the mass of the cathode increases as the reaction happens.

In the electrolysis of NaCl(aq) the half reaction for the oxidation of 2Cl- has a voltage of -1.36 V, while the half reaction for water has a voltage of -1.23 V. What is significant about this and how do you decide which reaction to use?

This is significant because the voltages are very close. It depends upon the concentration of the NaCl.

If the concentration of NaCl is low (dilute) in the electrolysis process, will the water or chloride ion get oxidized?

The water

If the concentration of NaCl is high (concentrated) in the electrolysis process, will the water or chloride ion get oxidized?

Chloride ion

If you are told there is an electrolysis of sodium chloride occurring and gas is being produced, what other piece of information do you need in order to find out if the Cl- or H2O is being oxidized? Why is the fact gas is being produced not sufficient?

You need to know if the pH is decreasing - decreasing pH means the concentration is low, so H2O is being oxidized. The gas is not sufficient information because both possible half reactions produce gas (H2O produces O2 and Cl- produces Cl2)

What are the three things you will observe in the electrolysis of copper II sulfate solution with inert electrodes?

1. The blue color will decrease because Cu2+ ions are being used 2. O2 (a gas) will be produced 3. The pH will decrease since H+ is being produced

How will the blue copper color change during the electrolysis of copper II sulfate solution with copper electrodes? Why?

The color will remain constant because the electrodes are producing Cu2+ while Cu2+ is also being used *Keep in mind this will only remain constant until the anode is fully turned into Cu2+ ions*

What is the purpose of electrolysis of copper II sulfate solution with copper electrodes?

To purify copper metal

Is the object that is being electroplated the anode or the cathode?

Cathode

What are the only three things the thickness of the metal coating in electroplating depends on?

1. How long the reaction is allowed to run 2. Current (amps) applied 3. Charge on metal ion

What is the equation to solve for the current in electroplating?

I=q/t I - current (amps q - charge (coulombs) t - time (seconds)

What happens to the concentration of ions in solution while electroplating?

They remain constant (until anode runs out)

What type of metal must the anode be?

Impure

What are the three uses for electroplating?

1. Decorative - plating jewelry 2. Protective coating - galvanized metal to prevent rust 3. Improve function

If a solid metal is put into a solution, in order to react does the solid have to be more or less reactive than the solution?

The solid has to be more reactive than the solution

In order for a species to reduce another species it has to be more likely to _____

More likely to be oxidized (have the most negative reduction potential)

If you do the electrolysis of a molten salt what will the products always be?

The pure metal and nonmetal

If you reduce H2O, will the pH increase, decrease, or neither?

Neither! H2 is produced

What is the overall redox equation for water? What is the ratio of moles of gas produced at the anode to cathode?

2H2O -> 2H2 + O2 1:2 (O2 is being oxidized at the anode, and there is 1 mole produced while there are 2 moles of H2 produced at the cathode)

How do you find the oxidizing and reducing agents in compounds?

Find which specific element is being reduced/oxidized and whichever compound it is in is the agent

Chemistry Unit 10 Flashcards

REDOX (64 cards)