C3 neutralisation and some electrolysis and other stuff-do both C3

state the overall neutralisation reaction

base + acid -> salt+ water

state the neutralisation reactions

metal oxide + acid -> salt + water
metal hydroxide + acid -> salt + water
metal carbonate + acid -> salt + water + carbon dioxide

formula for phosphoric acid

H3PO4

how do you calculate the concentration of hydrogen?

10 to the power of -(pH)

formula for hydrochloric acid

HCl

labelled reaction profiles

dont do bottom arrows

overall equation for electrolysis of aluminium oxide

2Al2O3(l) -> 4Al(l) + 3O2(g)

half equation for aluminium

[Al]3+ + 3e- -> Al

half equation for oxygen

[2O]2- = O2 + 4e-

what are halides containing?

containing group 7 (halogen) and metal ion

electrolysis of aqueous solutions rules are cathode and anode:

at cathode-less reactive element is discharged
at anode-if halide is present, it gets discharged. If not, hydroxide is discharged

when hydroxide is produced at the anode, what is formed and whtat is the equation?

forms water and oxygen
4OH- -> 2H2O + O2 + 4e-

what is the mnemonic for diatomic elements?

HOFBrINCl

what is formed at each electrode and what are the half-equations for electrolysis of sodium chloride solution?

cathode-hydrogen formed (2H+ + 2e- -> H2)
anode-chlorine formed (2Cl- -> Cl2 + 2CL-)

what could you use to measure pH?

• pH probe attached to pH meter, probe placed in solution and pH is given as numerical value on digital display-more accurate

• universal indicator

• other indicators-methyl orange, phenolphthalein, litmus

colours of methyl orange indicator:

• acidic-red

• neutral-yellow

• alkaline-yellow

colours of phenolphthalein indicator:

• acidic-colourless

• neutral-colourless

• alkaline-pink

colours of litmus

• red litmus

  • acidic-red

  • neutral-colourless

  • alkaline-pink

• blue litmus

  • acidic-red

  • neutral-blue

  • alkaline-blue

universal indicator colours:

• acids-strong to weak is red to yellow

• neutral is green

• alkalis weak to strong is blue to purplish

titration curves:

• show where neutralisation happens during a reaction

  • vertical point where solution is neutral- called the end point

how do you calculate overall energy change?

energy required ot break bonds-energy required to make bonds

describe technique of electrolysis using inert and non-inert electrodes:

• usually use inert electrodes eg platinum of carbon if products made are reactive

• non-intert electelectrodes can decompose into the electroyte eg copper elecrodes in solution of copper sulfate

• mass of anode will decrease and mass of cathode will increase because copper is transferred from the anode to the cathode

EXPLAIN what happens at the cathode in aqueous solutions

• less reactive one is reduced more easily/gains electrons more easily, so is discharged first