Electrochemistry

Question 1

What is electrochemistry? What is a current?

Answer 1

the branch of chemistry that studies the movements of chages that eventually gives us electrivity.

MAKES USAGE OF REDOX REACTIONS

1. an electrical flow created by the movement of the electrons

Question 2

What is a redox reactions?

Answer 2

single replacement reactions that allows the movement of electrons.

Question 3

which one is the oxidative agent and which one is the reducing agent?

Answer 3

1. Oxidation: atom eager to give an electron
2. Reducing agent: atom eager to receive electrons

Question 4

How is electricity form?

Answer 4

electricity uses the energy of redox reaction and the movement of electrons to do stuff:

1. Turn light on
2. Make railroad carts work
3. heating
4. cooling
5. computers working ect …

Question 5

What are the two ways that one can generate electricity?

Answer 5

1. Spontaneous: use a redox reactions that is already happening and connect a wire between the two parts of the reaction to allow electrons to go from one end (oxidation agents) to the other (reaction agent)
2. Non-spontaneous: a device such as a battery is used to drive the movement of electrons ( make use of EMF) which normaly does not happen with that specific reaction

Question 6

Explain the concepts of electrochemistry cells

Answer 6

these are device set up to use the energy of redoc and oxidatoin reactions in electrochemistry

Question 7

What is the concept of Galvanic or voltaic cells?

Answer 7

1. Spontaneous (-delta G): use reactions that naturally go through redox based on the nature of the different elements used.
2. Ecell: positive because the redox reaction wants to happen
   3.

Question 8

What is the reduction potential?

Answer 8

1. E-red measures the tendency of a chemical species to obtain electrons ( tendency to be reduce)
   
   1. higher E-red: they really want to reduce therefore is is spontaneous.
   2. Lower E-red or negative E-red: they really do not want to reduce so they may need helps from a device
2. Units: Volts or millivolts.

Question 9

What is an electrolysis?

Answer 9

1. When you need the help of a device such as a battery to drive the flow of an electron.
2. Non-spontaneous delat G (+)
3. Negative or low E-red or E-cell ( potential for movement of electrons to happen.)
4. Battery: provide the voltage ( or potential push) to drive the movements of electrons.

Question 10

What type of bonds can be find in oxidation reactions?

Answer 10

Ionic bond metals and non-metals

Concept:

1. remember that all atoms are trying one way or another to resemble noble gases in terms of their electron shells
2. Metals will give away their electons ( why they have the + charges) in order to resemble these atoms
3. While non metals will try and gain electrons in order to resemble these charges-
4. the difference between the two causes ionic bonds.

Question 11

Strategy to solving a redox reactions

Answer 11

1. Identify which one of the atom is oxidizing and which one is reducing. Understand how oxidation numbers works.
   
   1. break them up into 1/2 reactions
2. Take one 1/2 reactions and balance the atoms out
3. Next balance the Os with water (H2Os)
   
   1. in an acidic solution: balance the Hs of water with acid H+.
4. Add electrons (- E) to balance out the charges
   
   1. Balance oxidation number on each side of the equations (number before and after the arrow must cancel out)
5. Do the same exact thing for the other 1/2 reaction.
6. Add the balance 1/2 equation together
   
   1. Make sure electron numbers are equal for both equations redox/ oxi ( remember one give the electron to the other so they have to be equal, if needed multiply equations by a common number to make electrons equal)
7. Cancel what ever is the same on both side of the arrow
8. Count the oxidation numbers ( also has to equal for each atoms)

If in a basic solution: use OH instead of Hs

Question 12

what are the Oxidation rules

Answer 12

1. An atom by itself oxidation numner: ZERO ( except for diatomic atoms)
   
   1. monotropic ion: the charge based on the group it’s in
2. Group 1A always + 1
3. Group 2A always + 2
4. Polyatomic atoms is equivalent to their charges (memorize them)
5. Hydrogen
   
   1. With metals: -1 (metals usually have + oxidation numbers except for transisional metals)
   2. with non-metals: +1 ( non-metals usually want to gain electrons)
6. Oxygen
   
   1. usually -2
   2. except with peroxide than it is -1
      
      1. oxide: 0^-2
      2. Peroside: O 2 ^-2 ( if bonded to something else usually -1
      3. Superoxide: 02 ^-1
7. Fluoride: always -1

Question 13

What are anode and cathode?

Answer 13

1. Electron flow from ANODE to CATHODE

Question 14

What is a voltage?

Answer 14

• The difference between the area that has more electrons to give and the one that wants electons
• Is the pressure or force that drives the potential difference between the two ends
  
  • Batterries push that force in non-spontaneous reactions

Question 15

What is the equation to finding the Free energy change in an E-cell reaction? What is the connection with work?

Answer 15

1. will let us know if the reaction is spontaneous or non-spontaneous.

Delta G = -n (f) *E

• n: mole of electrons in the balance equations
• f: constant of charge: 96,500 C/ mol
• E-cell : J/C energy ( usually given)

1. Remember that work is energy:
   
   1. Work: difference in E =n* f * E

Question 16

What are salt bridges?

Answer 16

1. device that are used to keep the solution in the anode and cathod balance so that the electrons continue to flow.

Question 17

What is the nerst equations?

Answer 17

1. Use the nerst equation when you trying to find the Ecell potential under non-standard condition
2. Ecel= Ecell ( volt) - RT/nf ln (prod/react)

R =8.314 J/mol

T= Kelvin

n= moles of e

f feraday constant: 96500 c/ mol (cenversion factor of how many coulmomb is in one mole)