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 Post subject:
PostPosted: 2007-12-02 19:52 
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Joined: 2002-12-13 11:54
Posts: 839
Location: Nar Shaddaa
o gal kas galetu patarti is praktines chemijos puses?

Noriu pabandyt isesdinti ornamentus anti metaliniu sharvu
[ img ]
Kokia rugsty naudoti namu salygom, tai but gerai kad ne garais, o nuosedom reakcija gautusi. Ir dar kur tos rugsties pirkt ar is ko pasigamint?

"The decorator used a technique called “etching.” He painted designs on the steel plates with wax or varnish and then dipped the plates in acid. The acid ate away at the metal wherever it was not coated. Rubbed with a mixture of soot and linseed oil, these etched areas turned black, completing the design. "

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 Post subject:
PostPosted: 2007-12-03 0:33 
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Joined: 2004-04-22 18:10
Posts: 766
Location: didelis
dywa wrote:
Noriu pabandyt isesdinti ornamentus anti metaliniu sharvu
Kokia rugsty naudoti namu salygom, tai but gerai kad ne garais, o nuosedom reakcija gautusi. Ir dar kur tos rugsties pirkt ar is ko pasigamint?
ziurint is ko padaryti sarvai (koks metalas). bet paprasciausia isigyti butu druskos, sieros ar azoto rugsties (HCl, H2SO4 ar HNO3).

siaip bet koks metalas reaguodamas su rugstimi isskiria vandenili (kuris teoriskai sprogsta susimaises su oru). dujos is a must :)

Auksciau minetos rugstys yra stiprios ir turetu tirpinti greitai. as rinkciausi druskos, bet jei ji butu koncentruota (30%+), tai ji beveik garantuotai duotu visokiu duju. HNO3 yra stiprus oksidatorius ir su metalais pagal kanonus nereaguoja :) susidaro debesis bjauriu duju. sieros rugsties elgsena priklauso nuo koncentracijos, beto ji hidroskopiska.

duju galima bandyt isvengti naudojant druskas kaip tirpikli (pavadavimo reakcija). bet jau reikia ziuret konkreciai ir bet kuriuo atveju eksperimentuoti (pradeti ne nuo paradiniu sarvu ;) )

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 Post subject:
PostPosted: 2007-12-03 16:39 
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Joined: 2002-12-13 11:54
Posts: 839
Location: Nar Shaddaa
Siaip sarvai plieniniai.
"Copper plates and zinc plates are often dipped into ferric chloride solution and steel plates are dipped into nitric acid. Solutions are usually 2 parts FeCl3 to 2 parts water or for steel plate, 1 part nitric to 3 parts water. The strength of the acid determines the speed of the etching process. "
Teko akademijoje esdinti cinko ploksteles su skiesta azoto rugstim, tai sveikatos nepridave :roll:
Todel domina kiek imanoma saugesni budai...
kaip ten del drusku? gal galima placiau?

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 Post subject: Re: Chemija...
PostPosted: 2007-12-03 19:11 
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Joined: 2005-03-29 21:50
Posts: 75
Location: Vilnius
SeiRan wrote:
... Kaip reiktu mokytis chemijos? ... Ar atsiras tokiu kurie supranta ir pamokys arba bent jau nuoroda kokia parodykit ar siaip patarkit.
Imantis kokio darbo labai pravartu zinoti koki rezultata norima pasiekti. Tas 5-iu metu chemijos mokslu vidurineje rezultatas puikiai isdestytas populiariojoje enciklopedijoje "Mokslas ir visata" (psl. 128-153), bus kokie 6-7 lapai gryno teksto. Gal kur namie lentynoje guli tokia knyga :) paprastai buna padeta salia "Lietuviskosios tarybines enciklopedijos"

O uzdaviniai turi dvejopa paskirti:
1. padeti tau isisamoninti destomo dalyko pagrindus.
2. ismokyti deti pastangas sprendziant uzduotis.

Jei spresdamas uzduoti nusprendi, kad nieko cia nesupranti ir testi nera prasmes, tai pats sau uzsidedi kartele kurios negali perzengti. Nuo to kur uzsidesi kartele priklausys, ar ateityje sluodamas gatve spresi uzduoti S=vt, ar investiciju lygti su n kintamuju ir z nezinomuju.

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