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Question 1

how can a number y=b^x be written as a log

Answer 1

logb (y) = x

Question 2

how can ln x = y be changed to x =

Answer 2

x = e^y

Question 3

what does oxidation and reduction mean

Answer 3

oxidation - gain of electrons
reduction - loss of electrons

oil rig

Question 4

what does qualitatively and quantitatively mean

Answer 4

qualitatively - what substances there are

quantitatively - how much is present

Question 5

what is the daniell cell

Answer 5

copper plate in copper solution, zinc plate in zinc solution
salt bridge between the two
potential difference generated by the cell

copper was gaining electrons, zinc was dissolved into solution

redox occurred

metal parts are electrodes - solutions are the electrolytes

Question 6

what is an electrolyte

Answer 6

a liquid that can conduct electricity because ions have dissolved in it

Question 7

how to balance redox reactions

Answer 7

balance electrons on both sides through multiplication
add reactions together
cancel out anything on both sides

Question 8

what is a galvanic cell and electrolytic cell

Answer 8

galvanic cell - reaction is spontaneous when electrodes are placed in electrolytes eg daniell cell. battery

electrolytic cell - reaction is driven by external potential eg energy supply

Question 9

what is a cathode and anode

Answer 9

cathode - the electrode where reduction takes place

anode - the electrode where oxidation takes place

Question 10

what is activity in electrochemistry

Answer 10

the effective concentration of a chemical

activity = activity coefficient x concentration

temperature affects activity

Question 11

what is the nernst equation

Answer 11

E = E° - RT/nF ln(αred/αox)

E = actual cell potential (V)
E° = standard cell potential (V)
R = gas constant (8.314)
T = temperature (K)
n = number of electrons in reaction
F = faradays constant (96485)
αred = activity of reduced form
αox = activity of oxidised form

Question 12

what are the ways ions can move

Answer 12

diffusion - ions move from high conc to low conc

migration - ions are attracted to electrodes that are opposite charge

convection - movement caused by a mechanical force eg stirring or by change in density

Question 13

what is current

Answer 13

movement of particles eg electrons or ions

Question 14

what is resistance and conductance

Answer 14

opposition of flow of current

R = V / I

C = 1/R

Question 15

what equation is used to find pH

Answer 15

pH = -log10 [H+]

Question 16

what is conductimetry

Answer 16

the conductance of a cell using an ac electric supply between two calibrated electrodes. this varies with the distance between electrodes.

can be used to determine the purity of water

Question 17

what is volammetry

Answer 17

measuring the potential difference in a cell
uses 3 electrodes
concentration is proportional to diffusion current

graphed - voltammogram

Question 18

what are the types of electrodes

Answer 18

first kind - substances react directly with electrode

second kind - substance reacts with something else and then goes on to the electrode