faraday’s law. using faraday’s law, solve problems related to electrolytic cells additional key...
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FARADAY’S LAW
• Using Faraday’s law, solve problems related to electrolytic cells
Additional KEY Terms
Faraday (1791-1867)
• Coined terms "electrode", "anode", "cathode", "electrolyte", "ion", "anion" and "cation"
Amount of product formed at each electrode is directly proportional to the amount of
current passed through the cell.
• I is the current in amperes (A)• Q is the charge transferred in coulombs (C)• t is the time in seconds (s)
Current (I)• 1 coulomb of charge moving per 1 second
I = Q t
You have to memorize this formula
1 coulomb is BILLIONS of electrons worth of charge
1 mole e- = 96 500 C
1 F = 96 500 C/mol e–
Faraday (F) – the charge of 1 mole of electronsA single e- has a charge of 1.60 x 10–19 C
This is also called Faraday’s constant
Summary: We can use the formula for current combined with Faraday’s constant to calculate the mass of products in an
electrolytic cell
Determine the moles of electrons supplied by a battery with a current of 0.100 A for 50.0 min.
Q = I · t
= 0.00311 mol e-300 C · 1 mol e–
96 500 C
0.100 · (50min x 60 sec/min)Q = 300 C
Calculate a mass of aluminum produced by 7.50 A passing through molten aluminum oxide for 6 hours, 20 minutes and 10 seconds.
Al3+ + 3e– → Al
Q = I · t
= 1.77 mol e-1.71 x 105 C· 1 mol e–
96 500 C
7.50 A · (22810 s)Q = 1.71 x 105 C
You will always need the formula for what your are producing – you need to know the ratio of electrons
needed
Once you have moles you can find mass – using molar mass
1 mol Al27.0 g Al 1.77 mol e-
3 mol e-
1 mol Al
= 15.9 g Al produced
Al3+ + 3e– → AlUse the ratio of electrons needed
Every other question type is a variation of this procedure (some might give the mass and ask you to work backwards to current or time – you will
always need the net ionic formula for the metal, the current formula, Faraday’s constant
CAN YOU / HAVE YOU?
• Using Faraday’s law, solve problems related to electrolytic cells
Additional KEY Terms
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