Dear experts I want to make potash alum from scrap aluminium foil. Please look at the following procedure that i have found on the internet and answer the questions that follows . ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Procedure

? Clean a small piece of scrap aluminium with steel?

wool and cut it into very small pieces. Aluminium?

foil may be taken instead of scrap aluminium.

? Put the small pieces of scrap aluminium or?

aluminium foil(about 1.00g) into a conical flask and?

add about 50 ml of 4 M KOH solution to dissolve?

the aluminium.?

? The flask may be heated gently in order to facilitate?

dissolution. Since during this step hydrogen gas is?

evolved this step must be done in a well ventilated?


? Continue heating until all of the aluminium reacts.

? Filter the solution to remove any insoluble?

impurities and reduce the volume to about 25 ml by?

heating. ? ? ? ? ? Allow the filtrate to cool. Now add slowly 6 M?

H2SO4 until insoluble Al(OH)3 just forms in the?


? Gently heat the mixture until the Al(OH)3?

precipitate dissolves.?

? Cool the resulting solution in an ice-bath for about?

30 minutes whereby alum crystals should separate?

out. For better results the solution may be left?

overnight for crystallization to continue.?

? In case crystals do not form the solution may be?

further concentrated and cooled again.

? Filter the crystals from the solution using vacuum

pump, wash the crystals with 50/50 ethanol-water?

mixture. ? Continue applying the vacuum until the crystals?

appear dry.

? Determine the mass of alum crystals. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?#Respected experts please tell me 1)how shall i make 50 ml of 4M KOH solution ? If i add 11.22 gram of KOH pellets in 50ml of water will it do ? If not please elaborate each step clearly on how i can make it . ? ? ? 2) after filtering the solution of aluminium and koh how am i supposed to reduce it to? am i supposed to reduce it by heating ? ?3) how shall i make 6 M of h2so4 solution .... the procedure doesn't provide me with the amount of solution to be prepared in milli literes . Please tell me how i can make it . ? ? ? Last time i followed this procedure my crystals were not formed . I have to make this investigatory project as soon as possible so please help . My teacher said the koh pellets are very expensive , i have wasted them once and i need them to be perfect this time . Also how long am i supposed to keep the solution fir it to make the crystals ?

Dear Student,

‚ÄčUse the formula of Molarity to prepare 50 ml of 4M KOHWe know that,Molarity=massmolar mass×1000Volume of solutionor, 4=mass56×100050or, mass of KOH=4×56×501000=11.2 gSo, 11.2 g of KOH must be taken to prepare 50 ml of 4M KOHNow, further you can reduce the filtered solution to 25 ml by heating the solution. Heat the solution till 25 ml. 6 M H2SO4 can also be prepared by the above method. You just need to know the amount of solution you need to make.You can keep the solution overnight if crystals are not formed. You can also concentrate the solution more by heating and cool it if crystal doesn't appear. 

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