View source for Chemistry:Kipp's apparatus

{{short description|Laboratory device for preparing gases}}
[[File:Kipp Apparat.jpg|thumb|Empty Kipp's apparatus, with [[Engineering:Stopcock|stopcock]] and fermentation lock.]]thumb|Drawing of a filled Kipp's apparatus.'''Kipp's apparatus''', also called a '''Kipp generator''', is an apparatus designed for preparation of small volumes of gases. It was invented around 1844 by the Dutch pharmacist [[Biography:Petrus Jacobus Kipp|Petrus Jacobus Kipp]] and widely used in chemical laboratories and for demonstrations in schools into the second half of the 20th century.

It later fell out of use, at least in laboratories, because most gases then became available in small [[Physics:Gas cylinder|gas cylinder]]s. These [[Chemistry:Industrial gas|industrial gas]]es are much purer and drier than those initially obtained from a Kipp apparatus without further processing.

==Design and operation==
The apparatus is usually made of [[Chemistry:Glass|glass]], or sometimes of [[Chemistry:Polyethylene|polyethylene]], and consists of three vertically stacked chambers, roughly resembling a snowman.  The upper chamber extends downward as a tube that passes through the middle chamber into the lower chamber.  There is no direct path between the middle and upper chambers, but the middle chamber is separated from the lower chamber by a retention plate, such as a conical piece of glass with small holes, which permits the passage of liquid and gas.  The solid material (e.g., iron sulfide) is placed into the middle chamber in lumps sufficiently large to avoid falling through the retention plate.  The liquid, such as an acid, is poured into the top chamber.  Although the acid is free to flow down through the tube into the bottom chamber, it is prevented from rising there by the pressure of the gas contained above it, which is able to leave the apparatus only by a stopcock near the top of the middle chamber.  This stopcock may be opened, initially to permit the air to leave the apparatus, allowing the liquid in the bottom chamber to rise through the retention plate into the middle chamber and react with the solid material.  Gas is evolved from this reaction, which may be drawn off through the stopcock as desired.  When the stopcock is closed, the pressure of the evolved gas in the middle chamber rises and pushes the acid back down into the bottom chamber, until it is not in contact with the solid material anymore.  At that point the chemical reaction comes to a stop, until the stopcock is opened again and more gas is drawn off.

Kipp generators only work properly in the described manner if the solid material is insoluble in the acid, as otherwise the dissolved material would continue to evolve gas even after the level dropped.  The produced gas often requires further purification and/or drying, due to content of water vapor and possibly mist if the reaction is vigorous.

==Examples for prepared gases and their educts==
For successful use in a Kipp's apparatus, the solid material has to be available in lumps large enough to stay on the retention plate without falling through its holes.

*[[Chemistry:Hydrogen|Hydrogen]] from [[Chemistry:Iron|iron]] flakes or [[Chemistry:Zinc|zinc]] and [[Chemistry:Hydrochloric acid|hydrochloric acid]] or diluted [[Chemistry:Sulfuric acid|sulfuric acid]] respectively.
*[[Chemistry:Carbon dioxide|Carbon dioxide]] from pieces of [[Chemistry:Marble|marble]] ([[Chemistry:Calcium carbonate|calcium carbonate]]) and hydrochloric acid
*[[Chemistry:Hydrogen sulfide|Hydrogen sulfide]] from [[Chemistry:Iron(II) sulfide|iron(II) sulfide]] and hydrochloric acid
*[[Chemistry:Acetylene|Acetylene]] from [[Chemistry:Calcium carbide|calcium carbide]] and [[Chemistry:Water|water]]
*[[Chemistry:Methane|Methane]] from [[Chemistry:Aluminium carbide|aluminium carbide]] and lukewarm water, [[Physics:Deuterium|deuterated]] methane (CD<sub>4</sub>) from aluminium carbide and [[Chemistry:Heavy water|heavy water]]
*[[Chemistry:Chlorine|Chlorine]] from [[Chemistry:Potassium permanganate|potassium permanganate]], [[Chemistry:Calcium hypochlorite|calcium hypochlorite]], or [[Chemistry:Manganese dioxide|manganese dioxide]] and hydrochloric acid; also from [[Chemistry:Barium ferrate|barium ferrate]] and hydrochloric acid
*[[Chemistry:Oxygen|Oxygen]] from [[Chemistry:Calcium hypochlorite|calcium hypochlorite]] and [[Chemistry:Hydrogen peroxide|hydrogen peroxide]] with a bit of [[Chemistry:Nitric acid|nitric acid]]; also from [[Chemistry:Barium ferrate|barium ferrate]] and dilute sulfuric acid
*[[Chemistry:Ozone|Ozone]] from [[Chemistry:Barium peroxide|barium peroxide]] and concentrated sulfuric acid
*[[Chemistry:Nitric oxide|Nitric oxide]] from [[Chemistry:Copper|copper]] turnings and diluted nitric acid
*[[Chemistry:Nitrogen dioxide|Nitrogen dioxide]] from [[Chemistry:Copper|copper]] turnings and concentrated nitric acid
*[[Chemistry:Ammonia|Ammonia]] from [[Chemistry:Magnesium nitride|magnesium nitride]] and water, deuterated ammonia when heavy water is used;<ref name="WibergWiberg2001">{{cite book|author1=Egon Wiberg|author2=Nils Wiberg|title=Inorganic Chemistry|url=https://books.google.com/books?id=Mtth5g59dEIC&pg=PA267|year=2001|publisher=Academic Press|isbn=978-0-12-352651-9|pages=267–}}</ref> also from [[Chemistry:Calcium oxide|calcium oxide]] and solution of [[Chemistry:Ammonium chloride|ammonium chloride]]
*[[Chemistry:Carbon monoxide|Carbon monoxide]] from [[Earth:Pumice|pumice]] impregnated with [[Chemistry:Oxalic acid|oxalic acid]] and concentrated sulfuric acid
*[[Chemistry:Sulfur dioxide|Sulfur dioxide]] from pumice impregnated with [[Chemistry:Sodium metabisulfite|sodium metabisulfite]] (or sufficiently large pieces of sodium metabisulfite) and concentrated sulfuric acid, or from sodium hydrogen sulphite and concentrated sulfuric acid
*[[Chemistry:Hydrogen chloride|Hydrogen chloride]] can be prepared from lumps of [[Chemistry:Ammonium chloride|ammonium chloride]] and concentrated sulfuric acid<ref name="Erdey2013">{{cite book|author=László Erdey|title=Gravimetric Analysis: International Series of Monographs in Analytical Chemistry|url=https://books.google.com/books?id=MxkSBQAAQBAJ&pg=PA221|date=22 October 2013|publisher=Elsevier|isbn=978-1-4832-2259-2|pages=221–}}</ref>

Generally, weak acidic gases can be released from their metal salts by dilute acids, and sometimes just with water:<ref name="WibergWiberg2001"/>

* Hydrogen sulfide from metal [[Chemistry:Sulfide|sulfide]]s
* [[Chemistry:Hydrogen selenide|Hydrogen selenide]] from [[Physics:Selenide|selenide]]s, e.g. [[Chemistry:Aluminium selenide|aluminium selenide]]
* [[Chemistry:Hydrogen telluride|Hydrogen telluride]] from [[Chemistry:Telluride|telluride]]s, e.g. aluminium telluride
* Some hydrocarbons can be prepared from certain [[Chemistry:Carbide|carbide]]s 
** Methane from methanides
** acetylene from acetylides
** Methylacetylene and propadiene from sesquicarbides, e.g. magnesium carbide
* Ammonia from certain [[Chemistry:Nitride|nitride]]s, e.g. [[Chemistry:Magnesium nitride|magnesium nitride]]
* [[Chemistry:Phosphine|Phosphine]] from [[Chemistry:Phosphide|phosphide]]s, e.g. [[Chemistry:Calcium phosphide|calcium phosphide]] (often produced together with small amount of [[Chemistry:Diphosphane|diphosphane]])
* [[Chemistry:Arsine|Arsine]] from [[Chemistry:Arsenide|arsenide]]s, e.g. [[Chemistry:Zinc arsenide|zinc arsenide]]
* [[Chemistry:Stibine|Stibine]] from [[Chemistry:Antimonide|antimonide]]s, e.g. magnesium antimonide
* [[Chemistry:Silane|Silane]]s from some [[Chemistry:Silicide|silicide]]s (analogue of hydrocarbons, with number of silicon atoms corresponding to the silicide anion structure, sometimes more are produced from the same compound; e.g. silane, [[Chemistry:Disilane|disilane]] and [[Chemistry:Trisilane|trisilane]] from decomposition of [[Chemistry:Magnesium silicide|magnesium silicide]])
* [[Chemistry:Germane|Germane]]s from [[Chemistry:Germanide|germanide]]s, e.g. magnesium germanide
* [[Chemistry:Stannane|Stannane]]s from [[Chemistry:Stannide|stannide]]s, e.g. magnesium stannide
* [[Chemistry:Borane|Borane]]s from [[Chemistry:Boride|boride]]s (e.g. [[Chemistry:Tetraborane|tetraborane]] from magnesium boride, aluminium boride, or beryllium boride and an acid)
* [[Chemistry:Hydrogen fluoride|Hydrogen fluoride]] can be made from concentrated sulfuric acid and e.g. [[Chemistry:Calcium fluoride|calcium fluoride]]
* [[Chemistry:Hydrogen bromide|Hydrogen bromide]] can be prepared from [[Chemistry:Bromide|bromide]]s with concentrated [[Chemistry:Phosphoric acid|phosphoric acid]] (conc. sulfuric acid is too oxidizing)

A version of the apparatus can be used for reaction between two liquid precursors. A mercury trap has to be added as a check valve, and the middle bulb is filled with an inert porous material, e.g. [[Earth:Pumice|pumice]], onto which one of the precursors is dropped.<ref>{{cite web |url=http://users.humboldt.edu/rpaselk/MuseumProject/Instruments/Kipp-Erdmann/GasCurrents.htm |url-status=dead |archive-url=https://web.archive.org/web/20161225200917/http://users.humboldt.edu/rpaselk/MuseumProject/Instruments/Kipp-Erdmann/GasCurrents.htm |archive-date=2016-12-25 |title=Untitled Document}}</ref>

*[[Chemistry:Hydrogen chloride|Hydrogen chloride]] is prepared from hydrochloric acid and concentrated sulfuric acid
*[[Chemistry:Hydrogen sulfide|Hydrogen sulfide]] from concentrated [[Chemistry:Sodium sulfide|sodium sulfide]] solution and diluted sulfuric acid
*[[Chemistry:Sulfur dioxide|Sulfur dioxide]] from 40% solution of [[Chemistry:Sodium metabisulfite|sodium metabisulfite]] and concentrated sulfuric acid
*[[Chemistry:Nitric oxide|Nitric oxide]] from ferrous chloride in hydrochloric acid and 20% solution of [[Chemistry:Sodium nitrite|sodium nitrite]]
*[[Chemistry:Dinitrogen trioxide|Dinitrogen trioxide]], aka nitrous anhydride, from 20% solution of sodium nitrite and concentrated sulfuric acid
*[[Chemistry:Carbon monoxide|Carbon monoxide]], from concentrated [[Chemistry:Formic acid|formic acid]] and concentrated sulfuric acid.

==Further gas treatments==
The prepared gas is usually impure, contaminated with fine aerosol of the reagents and water vapor. The gases may need to be filtered, washed and dried before further use.

Hydrogen can be washed from sulfane, arsine and oxygen with subsequent bubbling through solutions of [[Chemistry:Lead(II) acetate|lead acetate]], [[Chemistry:Silver nitrate|silver nitrate]], and alkaline pyrogallic acid.<ref>{{Cite book | url=https://books.google.com/books?id=qwLgBAAAQBAJ&q=%22kipp%27s+apparatus%22&pg=PA161 |title = The Chemistry and Bacteriology of Public Health|isbn = 9781483195537|last1 = Dunn|first1 = C. L.|last2 = Pandya|first2 = D. D.|date = 2013-10-22}}</ref>

Acidic gases (e.g. hydrogen sulfide, hydrogen chloride, sulfur dioxide) can be dried with concentrated sulfuric acid, or with [[Chemistry:Phosphorus pentoxide|phosphorus pentoxide]]. Basic gases (e.g. ammonia) can be dried with [[Chemistry:Calcium oxide|calcium oxide]], [[Chemistry:Sodium hydroxide|sodium hydroxide]] or [[Chemistry:Soda lime|soda lime]].

Disposal of the gases can be done by burning the flammable ones (carbon monoxide, hydrogen, hydrocarbons), absorbing them in water (ammonia, hydrogen sulfide, sulfur dioxide, chlorine), or reacting them with a suitable reagent.<ref name="Erdey2013"/>

==Variants==
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Many variants of the gas production apparatus exist. Some are suitable for production of larger amounts of gases (Gay-Lussac and Verkhovsky), some for smaller amounts (Kiryushkin, U-tube).

A [[Physics:Döbereiner's lamp|Döbereiner's lamp]] is a small modified Kipp's apparatus for production of hydrogen. The hydrogen is led over a platinum sponge [[Chemistry:Catalyst|catalyst]], where it reacts with air oxygen, heats the catalyst and ignites from it, producing a gentle flame. It was commercialized for lighting fires and pipes. It's said that in 1820s over a million of the "tinderboxes" ("Feuerzeug") was sold.<ref>{{cite book|url=https://books.google.com/books?id=eFXWBgAAQBAJ&q=%22kipp%27s+apparatus%22+methane&pg=PA16| title= Principles and Practice of Heterogeneous Catalysis| first1=John Meurig| last1=Thomas| first2=W. John |last2=Thomas |format=Google Books|date=February 2015|edition=2nd|publisher=John Wiley & Sons|pages=16–17| isbn= 9783527314584}}</ref>

==Further reading==

* {{cite book | last = Griffin| first = John Joseph | title = Chemical Recreations: A Popular Manual of Experimental Chemistry | publisher = John Joseph Griffin  | year = 1860 | edition = 10 | page = [https://archive.org/details/chemicalreactio01grifgoog/page/n527 616] | access-date = 2007-11-12 | url = https://archive.org/details/chemicalreactio01grifgoog | quote = kipp's apparatus.}}
* {{cite journal | author = Sella, Andrea | title = Kipp's Apparaatus | journal = Chemistry World |date=November 2007 | pages = 81 | access-date = 2007-11-13 | url = http://www.rsc.org/chemistryworld/Issues/2007/November/ClassicKitKippsApparatus.asp}}
* [http://mattson.creighton.edu/History_Gas_Chemistry/Kipps.html Kipp's apparatus] - extensive explanation with pictures and references

==References==
{{Reflist}}

==External links==
* [https://www.youtube.com/watch?v=2cWa5ENWxAg Demonstration of Kipp's apparatus] at The Periodic Table of Videos

{{Laboratory equipment}}

[[Category:Laboratory equipment]]
[[Category:Industrial gases]]

{{Sourceattribution|Kipp's apparatus}}