Alright yall let's make a thread of STUFF WE GOTSTA KNOW
GOGOGOGOGOGOGOGO!!!Here's some stuff to kick us off:
Nuclear Fusion
Energy stored in plants:
+6H_2O(l) \rightarrow C_6H_{12}O_6(aq)+6O_2(g))
Combustion of coal in a power station
+O_2(g) \rightarrow CO_2(g))
Oxidation of sulfur impurities in the coal
+O_2(g) \rightarrow SO_2(g))
(courtesy Kilbaha '09)
- Catalysts speed up reactions by providing an alternative pathway of lower activation energy. Reactants adsorb to the surface of catalysts where they meet and react. Catalysts do not affect equilibrium yield.
- Only temperature can affect the equilibrium constant!
- The conditions for the electrochemical series are 1M, 25 degrees celcius, and 1 atm (e.g. Brine > 1M, so Cl(g)/Cl- drops below the water reaction)
\rightarrow H_3O^+(aq)+OH^-(aq))
ENDOTHERMIC
- You can only recharge cells if the products of the discharging reaction do not leave the surface of the electrodes
- If you are electrolysing a solution containing Cl- ions, even though Cl(g)/Cl- is higher than the water reaction, thre is chance that Cl(g) will be given off if the voltage is high enough.
- In a secondary cell, no matter whether you're charging or discharging, the negative electrode stays negative, and the positive electrode stays positive. However, anode and cathode swap.
- If asked to derive
, find
})
- If asked to derive
, find
}{n(X)})
where X is anything. Do not use Faraday's constant, it is itself derived from
- If you dilute a strong acid its pH will change more than for a weak acid. This is due to it already being fully ionised. The weak acid will ionise more if you dilute, due to LCP.
- If you need to draw a half-cell and one of the reactants is a gas, you need to draw a gas electrode (there's a pic in your heinemann textbook)
- In oxygen-hydrogen fuel cells, electrodes must be catalytic and porous. In general they must also be inert and conducting.
- You must use Brine in a membrane cell (producing Sodium hydroxide). It is concentrated NaCl, which allows the Cl(g)/Cl- reaction to go below the water reaction on the electrochemical series.
- The Down Cell (producing Sodium) must use molten NaCl
- You must use Cryolite in a Hall-Heroult Cell (producing aluminium) (you don't need to remember the formula of cryolite), in order to lower the temperature required for the reaction.
- The electrochemical series cannot predict the rate of reaction. Don't even try it.
- In a galvanic cell the ions in the salt bridge must be soluble, but also inert.
- Inert electrodes include Graphite and Platinum, with the former being more expensive but also having some catalytic properties.
-
It can be negative!
- An equation
does not imply that the concentration graphs will start with
NO! The equilibrium constant must always be obeyed! To differentiate between species on a graph when they have not been labelled, refer to next dot point
- In
, any changes driven by LCP will involve the graphs increasing/decreasing in ratio 1:2:1 for A:B:C
respectively. i.e. the number in front of the chemical will govern how much the graph of that chemical increases/decreases due to LCP.
- Faraday's Laws
1.
(m is mass deposited)
2. In order to produce 1 mole of metal, a whole number of mole of electrons must be consumed.
- Biochemical Fuels
Fermentation of glucose to ethanol:
 \rightarrow 2CH_3CH_2OH(aq)+2CO_2(g))
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